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Unique Melody Platform Pure | PP6 Review: Active euphoria

Unique Melody is no stranger to making high quality custom IEM products as they have been a favorite in the audiophile world and on head-fi for years.  The Miracle and Merlin are very well reviewed, however I have only heard poor performing demo units.  The Platform Pure | PP6 is UM’s new flagship that takes the next step by utilizing active crossovers to the mix, which is achieved in an external unit that of course has a built in DAC and 6-channel amp.  This flagship product is my first opportunity to hear a customized UM product, which is exciting considering the popularity, technology, and high expectations.

How to Order, Warranty, Options

Unique Melody is based in China, however they have other branches in the US, Germany, Russia, Japan, and Australia that handle orders.  The Unique Melody PP6 is $2,280 without artwork.  The US how to buy page is here.

Options: The US site has a custom in-ear monitor designer here.  Passive crossover cable will be available in the near future.

Warranty: The PP6 comes with a 2 year warranty, 60 day free refit.


The PP6 earphones incorporate 3 dual balanced armature drivers, each with their own sound tube, for a total of 6 drivers in an acrylic shell without any crossovers.  The connector is a unique 4-pin round connector with an alignment key and the box has a pressure lock connector.  Inside the box there is a DSP, DAC, and 3 separate amps.  The box has 4 inputs: USB (micro), coax, optical, and line.  It is uncertain the signal path of the line in. There is a source selector, volume knob, and bass boost switch on the front and an on/charge switch on the back.

(images courtesy of UM Australia)

Frequency response: 10H~23KHz
Low frequency stereo isolation: 56 dB (100Hz)
Mid frequency stereo isolation: 56 dB (1KHz)
High frequency stereo isolation: 56 dB (10KHz)
Total harmonic distortion: 0.002% (10mW)
SNR: 102 dB
6-Channel Amplified Analog Output: >100mA per channel
Digitally controlled variable bass output: +0dB/+6dB/+9dB Boost
USB: supports 24Bit/96KHz input
Optical/Coaxial: supports 24Bit/96KHz input
Playback time: ≥7h
Charging time: ≤8h
Battery capacity: 3000mA

Top chart: Phase Lower chart: Frequency response

Phase&Freq Response - Unique Melody Platform Pure 6 | PP6 Active Custom In-Ear Monitor


The PP6 comes in an exquisie box with a 50″ Silver cable, 50” black Cable, USB cable, and cleaning tool.  While the box looks very nice, it isn’t too practical for portable use as you must disconnect the CIEM cable from the box and my large shells don’t fit well in the box.


The PP6 comes with two cables at this time, a black cable and a silver colored cable.  Both use 8 conductors and are reminiscent of a standard twisted CIEM cable, but thicker due to the additional wires.  The ergonomics are very good and the performance is very similar to stock twisted CIEM cables.  The connector for the box uses a pressure lock connector that clicks in place once aligned and is disconnected with a pull on the spring loaded ring.  The shell connectors are unique 4-pin connectors with an alignment key.  They are slightly loose on my unit, but a mention to Stephen from UM USA resulted in a change as they will add more acrylic to the shell for a tighter fit.  The silver colored cable will oxidize over time and the black cable, which I have been using, could use more twisting on the portion between the Y-split and shell connections. 

Fit & Finish

Unique Melody has a reputation of providing a very good fit and finish and my PP6 shells live up to the high expectations.  The white faceplates are have an impressive look, both shells are free from bubbles, and the finish is nice and smooth.  The PP6 fit is excellent with no issues.  The cable is nice, however as mentioned in the cable section, the braiding above the Y-split is unraveling a bit.  The box is very well constructed and mechanically everything works well.


The PP6 is not your typical CIEM as it has a separate box that contains the crossover, DAC, and amps, so until the external crossover cable is included, the box is required.  The box isn’t cumbersome and is on par with many amps, but it does change the dynamic of the PP6 usage as there is an extra box to carry around.  This makes tiny rigs such as the Zip Clip, iPod Nano, or Hisoundaudio RoCoo become much larger.  It does make the PP6 a bit difficult to use unless you make specific carrying appropriations for it, but on the flip side, you get specifically tuned amps and an active crossover that result in an amazing sound quality from just about any way the PP6 is sourced.

Once the passive crossover cable is available the usability should be the same or similar to other CIEMs, depending on how the crossover is implemented.


Isolation is slightly above average for an acrylic shelled CIEM. My unit rates as a 6/10, however isolation can be improved by adding additional layers of acrylic for the shell if requested.


Disclaimer: My review is a comparative review, and since I have many similarly priced custom IEMs, my perspective is based on equal competition.  My goal is not to tell you how great the item being reviews is, but to explain the sound signature and characteristics as well as bring you a balanced account of the strengths and weaknesses to help you decide if this particular custom IEM is for you.  When I listen to custom IEMs without any comparison after some time away, I am continually impressed with the sound and it is the contrast that enables my perspective.  So take the review as a critical look at the custom IEM and realize there will be positive and negative aspects of every product I review and product selection should be based off what sound signature you want or the purpose of your purchase instead of looking for technical top performance.

Quick reference: My review technique, Thoughts on reading a review, Custom IEM information

The PP6 received 100+ hours of burn in as is customary before I do my serious listening.  Because there is the DSP/DAC/amp box, I decided to increase this number dramatically by letting the PP6 play continuously.  The following custom IEMs were used for comparison: Ultimate Ears Personal Reference Monitor, Spiral Ears SE 5-way Reference, Hidition NT-6, Hidition NT-6 Pro, M-Fidelity SA-43, and Rooth LS8.  Sources used for comparison include the HiFi Man 801, Leckerton UHA-6S MKII, and Anedio D1.

Bass: The bass is deep, plentiful, powerful, and enhanced (with a source like the DX100) for a combination that will please most, and that is without the optional +6 or +9 dB bass boost.  Without the boost on, the bass has nice control, although a few CIEMs such as the NT-6, NT-6 Pro, and UE PRM perform slightly better in this regard.  While the NT-6 Pro has a similar amount of rumble, the NT-6’s more neutral bass and the PRM’s single driver don’t convey quite the power of the PP6 in part due to the enhancement.  Capability to sustain bass notes is exceptional and only the SE5 bests the PP6 when SE5 is powered by a high performance amp or source, and only by a small amount.  Bass detail, texture, and resolution levels are good and near the top of the performance ladder, but a few other CIEMs outperform the PP6.  While the bass is enhanced it isn’t as enhanced as the JH16 or 8.A.  There is a warmth to the presentation, but there are many other CIEMs that have more warmth.

Switching the bass boost switch to the +6 dB setting increases the bass and warmth resulting in a richer, fuller sound that is sometimes very good and sometimes a bit much.  The boost doesn’t affect the rest of the frequency spectrum, but there obviously is a tonal shift which moves the sound signature closer to that of the 8.A and 5-way.  Source has a large effect on how well the boost performs as the DX100 makes the +6 dB boost sound a bit bloated compared with my modded iPod that sounds quite good and well controlled.  When paired with my modded iPod with the +6 dB boost on the sound reminded me of sitting in a room in an hi-fi stereo store listening to very expensive full sized speakers with a perfectly integrated subwoofer.

The PP6 also has a +9 dB bass boost setting that is usable with select sources such as the Hisoundaudio products and the iPhone to an extent.  The sounds gets thicker and more bass focused, but with a source such as the DX100 it becomes bloated and somewhat muddy, at least compared with other high end CIEMs.   I can see a use for the +9 dB bass boost due to both preference and source matching, such as the Hisoundaudio RoCoo BA or Power.  Plus, the bass boost can be a benefit when there is a lot of background noise or during quiet listening sessions when you want to compensate for the human loudness curves.

Putting it all together, the bass enhancement will depend upon the source used as some source pairing benefited from the bass boost while others didn’t need it.   The PP6 bass combines power with refinement in an engaging way that can convey real power, ranking it among a short list of exceptional all around performers.  The bass boost options are going to depend on the source used to feed the box, as sometimes a +6 dB or +9 dB boost can be a very rewarding experience, conveying the power and authority the PP6 is capable of recreating.

Midrange: There are so many good things to say about the PP6 midrange due to the smooth yet refined and 3D presentation that has a nice balance between being forward and laid back.  In comparison with the bass and treble regions of the PP6, the midrange is laid back, presenting an excellent sense of space.  While the PP6 doesn’t have any weaknesses per se, the biggest issue with the PP6 midrange is the level of detail, which is most apparent when compared with CIEMs such as the NT-6, SE5, LS8, and JH16.  Instruments have good detail, but the fine nuances are more difficult to hear and the space between instruments and room ambiance is not resolved as well as the NT-6, NT-6 pro, or SE5.  However, with that said, the presentation is more laid back than the others which is makes sense that a more laid-back performance wouldn’t have the details of the instruments like an up-close presentation.  Overall the PP6 midrange is very natural and performs well considering the way it is presented.

Treble: The PP6 treble is bright, but not too bright, as something like the NT-6, NT-6 pro or LS8, achieving a nice balance for those that like treble, but don’t want too much.  Detail levels are very high and only slightly lower than the SE5, but there is a bigger gap vs. the more analytical NT-6 and NT-6 pro.  Note decay is very good, with a realistic and smooth decay resulting in a sound that is very enjoyable. The presentation of the treble is a bit more forward than the midrange starting from the upper midrange through the treble forming the upper part of the U shaped sound signature.  The treble has very good extension, although it does roll off slowly to my ears past 15K.  Overall the PP6 treble combination of smoothness, detail, and note decay make the treble one of the best I have heard.

Presentation:  If I were to quickly sum up the presentation of the PP6, spacious and smooth with a U shaped sound signature would be the quick and dirty.  The soundstage presentation is very spacious with the closest performance to the SA-43 that I have heard, but not quite as laid back, which doesn’t make the PP6 mid-forward.  It is actually somewhat laid back in midrange and the distance from the presentation is further than typical.  Soundstage proportions are good, and while there is very good depth, select others have a bit better depth.  Imaging is very good and the overall soundstage presentation is very believable. 

The PP6 disappears and lets the music come through with excellent transparency and coherence from top to bottom, although the integration between the midrange and upper midrange/treble isn’t blended as well as some of the competition.  Dynamics are very good with plenty of punch and impact when needed, although due to the note thickness, notes aren’t overly punchy.  For example, the JH16 can feel like a kick to the head from a stack of subs while the PP6 feels more like a bass punch from an 18” subwoofer.   As far as note thickness, the PP6 strikes a very good blend between thin/analytical and thick/warm resulting in a neutral sound that is musical yet technically excellent.  This note presentation doesn’t give the PP6 a sense of speed like some of the competition such as the NT-6 pro, but that doesn’t mean the PP6 lacks speed as can be heard with fast music such as speed metal.  The PP6 is quite forgiving due to the combination of sonic characteristics and works with every track of varying quality and genre I have thrown at it.


Since the PP6 uses its own internal DAC, I used the Anedio D1 DAC or DX100 with the competitors for comparison.

Ultimate Ears Personal Reference Monitor: The PP6 is more spacious, airy, and bright compared with my tuning of the more mid-forward PRM.  Notes are thicker on the PRM resulting in the PP6 having a cleaner and clearer sound.  Detail levels are similar, as is resolution, but the PP6 images better and has a wider and deeper soundstage.  Transparency and coherence are similar, but the PP6 has better dynamics and speed.  While both are smooth, the track determined which was more forgiving.

Keeping the bass boost switch in the off position still results in the PP6 having more bass than the PRM in quantity, which is tunable on the PRM so quantity could be similar, but the PP6 can sustain bass notes better.  Bass quality is similar between the two.  The PRM is warmer than the PP6, and while that is tunable, there is warmth from a thicker note.  The midrange is divergent as the PP6 strikes a good balance between laid back and forward while the PRM is more forward, bringing vocals closer to you, but the smaller soundstage and closer midrange make it sound a bit small in comparison.  The upper midrange of the PRM seems a bit artificially boosted in comparison with the PP6 and without using a PRM tuning box with the PP6 present, I am not sure if the gap can be closed.  While the PP6 has more treble energy than the PRM, the quality of the treble is superior with the PP6. 

There are times when in direct comparison, one CIEM sounds much better than the other, and this is the case here as the PP6 sounded more natural and realistic to my ears due to the differences in upper midrange.  This is not an issue with the PRM vs. other CIEMs.  Both of these CIEMs offer something unique as the PRM can be tuned to your preferred sound signature while the PP6 uses an active crossover, 6 amps, and an internal DAC along with adjustable bass boost.  If you want a more mid-forward sound, the PRM is a good buy, and if you want a U shape with a clean and clear sound, the PP6 is excellent. 

Spiral Ears SE 5-way Reference: The sound signature of these two varies quite a bit as the 5-way is more mid-forward with a very organic sound while the PP6 has more spacious and enhanced sounding presentation.  Instrument detail is a bit higher with the 5-way with nuances, faint sound, and room reverb is easier to hear, giving the 5-way an advantage in overall presentation resolution.  The soundstage proportions are close, but the 5-way has a near perfect balance between width and depth while the PP6 has a slight bit more width than depth, but imaging is similar.  While the PP6 has very good note attack and decay, the 5-way has more capability to play a wider range of note thicknesses and speeds from the delicate to the powerful.  Transparency and coherence are very close and clarity of the PP6 is just a hair behind the 5-way.  Overall the PP6 is more forgiving, but when a track has poor treble quality  the 5-way handles the track in a less offending way.

With the bass boost on the PP6 box set to the minimum, the bass of the PP6 is quite close to the 5-way, however the 5-way does have a little bit more ability to sustain notes and presents with more texture.  The 5-way is warmer with a warmth and richness that continues up to the midrange.   The midrange of the 5-way is more up-front and also has excellent presentation depth resulting in an immersive experience while the PP6 comparatively has a laid back midrange that gives more of a sense of distance from the presentation.  The upper midrange and treble are pulled a bit more forward on the PP6 and the overall tone is different with the 5-way having an organic touch to it and a longer note decay while detail levels are close.

With two different sound signatures and configurations, the PP6 offers a more laid back and spacious presentation with a U shape to the frequency response compared with the more upfront 5-way that has a flatter overall frequency response.  While the 5-way technically beats the PP6, it is close, and the total cost of the 5-way with a good source to help it reach its full potential cost more than the PP6.  At this level in general, cost is no object, so select what will fit your sound signature preferences.

Hidition NT-6: The NT-6 has a neutral “reference” presentation that is brighter, more mid-forward, and airier in comparison with the more spacious and bass emphasized PP6.  Soundstage proportions are similar, although the PP6 is ultimately bigger overall most of the time, but the NT-6 does scale up with spacious tracks.  Clarity of the presentation is superior with the NT-6 as is detail and overall resolution resulting from the more analytical average note weight.  Both are dynamic, although the PP6 does have slightly better dynamics, and note attack and decay capability is similar.  The PP6 is more forgiving due to the smoother, more liquid presentation. 

The PP6 is more bass enhanced with more rumble even though the NT-6 bass has similar capability.  While the bass of the PP6 is very high quality, the more neutral NT-6 is a bit cleaner and more detailed.  The warmth of the NT-6 changes quite a bit with each track, but the PP6 is generally warmer.  The slightly more forward midrange of the NT-6 conveys more information in a cleaner and clearer way with more emphasis on instrument detail in comparison with the PP6’s masterful recreation of the overall presentation.  Vocals have a higher tone with the NT-6 and can be a bit on the harsher side when compared with the PP6.  The upper midrange through the treble is more prominent with the NT-6, although the PP6 does have an overall emphasis in the treble region.  Decay and quality of the treble is similar, but the PP6 has a smoother and more forgiving treble vs. the more detailed NT-6 treble.

With two different sound signatures, price points, and features, these two are made for different purposes.  The PP6 is an audiophile’s design for use with a wide range of genres and tracks while the NT-6 can be harsh with poorly mastered material, but works well as a studio monitor.  With a comparative bass tilt, the sound of the PP6 is spacious and fun with a smoother presentation On the other hand, the brighter and colder NT-6 will reveal everything in your music, good or bad due to the clean, clear, and analytical sound.  If you want a more consistent presentation across your music and/or want a fun sound with a bass enhancement, the PP6 is it.  If you work in a studio or want to hear everything and can handle a bright sound signature, the NT-6 is a great option.

Hidition NT-6 Pro: The PP6 is mid-forward with a thicker average note in comparison with the NT-6 pro, but the rest of the frequency spectrum is similarly presented.  The soundstage size is very similar and while the PP6 is slightly wider, the NT-6 pro has better presentation depth.  Both image well, but the NT-6 pro edges out the PP6.  The more liquid PP6 has equal dynamics and transparency, with coherence that is very close, but the NT-6 pro is clearer with a better focus on the music, and more detail, resolution, and note speed when called for.  Notes are thicker and smoother on the PP6 which leads to a more forgiving presentation.

While the bass quantity is similar, the NT-6 pro has a bit less upper bass/mid-bass emphasis than the PP6 and the NT-6 pro bass is more precise and detailed.  The warmer PP6 has a midrange that is more forward, thicker, and brings vocals closer to you, although NT-6 pro midrange is noticeably cleaner in contrast to the richer PP6.  The NT-6 pro is brighter than the PP6 from the upper midrange on up, and although the NT-6 pro treble is of very high quality, it has sharper Ss in comparison to smoother presentation of the PP6.

The PP6 and NT-6 offer similar performance, but the PP6 integrates a high end source for the extra money.  If you want a smoother, more liquid performer that has less treble and more warmth that is very musical and fun, the PP6 is the choice.  In contrast the NT-6 pro is brighter, a bit colder, and more analytical, but also offers insane clarity and higher levels of detail.  Both are extremely enjoyable and can offer euphoric musical enjoyment.

M-Fidelity SA-43: This comparison is being made mainly for soundstage size references using the DX100 -> Portaphile 627.  This is the first time I have used the SA-43 with this source combo, which brightens the sound of the SA-43 a good amount.  Diving right into the presentation, the soundstage is fairly close, although the PP6 is a bit more mid-forward and slightly smaller in width while there is a larger gap between the deeper SA-43 and PP6.  On top of that, the SA-43 images better and presents the soundstage in a more realistic way than the PP6.  Transparency is very similar and the SA-43 is slightly more coherent across the frequency spectrum.  However, in just about every other technical category such as dynamics, speed, and detail, the PP6 bests the SA-43 from a little bit to a good amount and can make the SA-43 sound a bit unrefined in the treble region. 

Comparing the bass was interesting since both the SA-43 and PP6 have bass adjustment capability.  The PP6 with no boost was similar to the SA-43 with the extra bass driver turned on, although the PP6 still had a bit more bass.  With midranges that are presented similarly the differences come down to refinement and detail levels, which are superior with the PP6.  While the treble of the SA-43 is high quality treble, the PP6 treble is cleaner, smoother, and more realistic with more detail.

The PP6 comes close to the SA-43 in presentation space, but does fall a bit short while besting the SA-43 in most other technical categories.  Since the SA-43 requires a strong amp while the PP6 comes amped, the price gap is narrowed.  Even using a fantastic amp such as the Portaphile 627, the SA-43 still doesn’t perform up to the level of the PP6 with one exception: soundstage realism and size.  If you are a soundstage junky, the SA-43 might be your best bet, but if you value the other aspects, the PP6 is a great choice.

Rooth LS8: The more spacious PP6 has a warmer overall tone in comparison with the brighter and more forward presentation.  Spatially, the PP6 outperforms the LS8 in every way from width to depth to imaging to instrument separation.  Clarity between the two is similar, but the brighter presentation of the LS8 plays a larger part in this result.  Both are dynamic and punchy, but the PP6 performs better.  Transparency is a bit better with the PP6 while coherence is a good deal better.  Overall detail levels are similar, but relative performance varies depending on the frequency.  The PP6 is more forgiving of poorly mastered tracks.

While the bass presentation is close, the PP6 outperforms the LS8 in both power and detail, sounding cleaner and clearer down low.  Warmth is similar, although the PP6 tends to sound a bit richer.  The midrange of both are fairly similar, but the PP6 is more realistic in how it paints the picture with a more 3D presentation and better imaging.  The upper midrange of the LS8 is turned up in comparison and the treble region and the LS8 treble is more detailed, although not as smooth as the PP6.

There is a lot to like from both with the LS8 offering a brighter sound that is more detail up top in comparison with the more spacious and richer PP6 that has a better low end and midrange.  The choice between the two comes down to how bright you want your sound and how much you want to spend: save and get a brighter presentation that is very good, of spend and get a more balanced presentation with higher technical ability.

Volume performance:

The volume control of the PP6 has issues at the lowest position of the volume knob since the sound becomes scratchy, sounding like a badly scratched CD with lost data.  This can be problematic for low volume listening from any source that doesn’t have volume control, such as the optical and coax out of the 801 and DX100.  The PP6 performs well at all other volume levels.

Sound Summary:

The PP6 is a marvel of sound.  Many times when I stuck them in my ears I was lost in the music vs. trying to review them and when listening to a sub-$1K CIEM and then switching to the PP6, the overall step up in sound quality was quite noticeable.  The presentation is spacious, smooth, liquid, detailed, transparent, dynamic, and very capable in the bass department with a U-shaped sound is more on the fun and colored side than the reference side of the spectrum.  With a balance between the warm and organic such as the SE5 and the bright such as the NT-6, the PP6 has an inoffensive treble that won’t leave most wanting more.  Average note weight is an excellent balance between analytical and organic resulting in a very musical and euphoric presentation.

Technically the PP6 competes for the top spot in most of my rating categories, but is usually just a bit behind the top performers, with the biggest discrepancy being in the reproduction of fine details and ambiance.  Overall, the technical performance is near the top of my rating system, and the PP6 offers a unique sound signature in doing so.

The DAC, crossover, amp box

The PP6 comes with a box that contains a DAC, active crossovers, and a six-channel amp.  Inputs include coax, optical, USB, and auxiliary for a line input.  There is a selector button to switch between the sources.

Since it isn’t possible to determine the performance of the box without an external crossover cable, which isn’t out yet, the PP6 box and CIEM must be evaluated together.  From what I know about other UM products, the box isn’t holding the CIEM back, and is leading to the spacious presentation and excellent refinement.  Unfortunately, at this time there is a low level hiss between tracks, but UM is working to resolve this.

Source matching

Unique Melody Platform Pure 6 | PP6 Active Custom In-Ear Monitor with iBasso DX100

 Portable Sources, DAPs

iPhone 5 – line out: So, you have your $2,280 PP6 and use your iPhone 5 as a source; I can see it happening.  Considering the external box houses the amps, the PP6 sounds impressive.  The weak link of the iPhone is the level of detail, and the PP6 somewhat masks that issue due to the box.  When comparing the iPhone 5 with the RoCoo BA, the iPhone 5 sounds less dynamic, detailed, and spacious; however if you do use an iPhone 5 the PP6 sounds excellent in the grand scheme of things, considering other CIEMs.  The rating is indicative of the large amount of improvement attainable with other sources. 3/10

RoCoo BA – line out: Using the headphone out of the RoCoo BA, the PP6 gains a nice 3D space that is a step up from the iPhone 5.  But, when compared with the 801, the room for improvement is revealed as the 801 is more resolving, spacious, and smooth.  The BA is a nice source given the price if you have one, but if you don’t it is a questionable addition. 4/10

801 (with GAME card) – line out: The 801 does the little things right with the PP6, adding spaciousness in the form of presentation depth while increasing layering and detail with a smooth, organic note.  The result is a very transparent sound that is pleasing to hear, allowing me to forget about the equipment and focus on the music.  9/10

DX100 – line out: While the 801 sounds very good with the PP6, the DX100 line out takes things a step further with additional clarity, detail, instrument separation, and realism.  This combo has excellent conveyance of emotion and power in my music.  Also, the line level output is controlled by the volume control on the DX100, so you can pair these two and have a good low volume level listening experience.  10/10

DX100 – optical, coax: I could hear no discernible difference between the optical and coax inputs from the DX100.  I figured I would be able to hear some difference between the line in and the optical/coax in from the DX100 and was easy enough to compare, with the touch of a button.  After quite a while listening for any difference I finally found something after about 10 songs: in Oye Como Va, the background sounds are slightly more refined and a slight bit more spacious.  The fact that I had to try multiple songs and really pay attention to any possible differences either means the DX100 line out is exceptional, the PP6 line in is done right, or a combination of both.  If you want something shorter than the coax cable included with the DX100 the line input is a viable option.  Note that I used was Whiplash SCag wire interconnect.  Plus, the line out volume is variable while the coax and optical levels are not, reducing the score due to low level volume issues. 9.5/10

Desktop Sources

PP6 USB input: The PP6 USB transport to DAC is a good, however it is hard to judge exactly how it performs since the CIEMs can’t be used with other sources.

UHA-6S MKII – line out: After extensive A/Bing with a simple button press to change the PP6 box source, the differences between the two are so minimal they are barely worth mentioning.  The MKII is ever so slightly brighter while the PP6 DAC is slightly more mid-forward.  The differences are extremely small.

801 – line out: No discernible difference from the 801 used as a DAC vs. the PP6 internal USB driven DAC.

D1 – line out: The output is a bit richer and more organic than the USB input of the PP6.

Musiland Monitor 01 USD – optical: Minimal differences that include a tiny boost to the bass and a slight bit more spacious soundstage.  The sound is overall a bit livelier but also not quite as smooth, especially in the upper midrange and treble with female vocals.

Source Summary: The Unique Melody PP6 box performs well regardless of what drives it, but there are benefits when paired with higher end sources.  Coax, optical, and line in all perform quite similar and the internal USB DAC doesn’t take anything away.  Using a source with a variable output will help eliminate the low volume level issues with the volume pot.


Unique Melody Platform Pure 6 | PP6 Active Custom In-Ear Monitor

The Unique Melody Platform Pure 6 | PP6 is a work of art and nice piece of hardware that gets out of the way and lets the music shine through.  With top tier technical performance combined with a spacious presentation, very a special combination of power and refinement in the bass region, and a fun sound signature, the PP6 recreates emotion and musicality across every genre I threw at it.  The PP6 will please fans of bright sound as well as those that don’t like overly bright sound.  I could go on as the PP6 is dynamic, images well, and has a very natural treble that stands out from much of the competition.

The box includes plenty of inputs including USB, optical, coax, and line in, and is portable with a 7-8 hour battery life.  UM is working on a passive crossover cable, but it isn’t ready at this time.  The PP6 isn’t perfect as the box is required at this time, there is some hiss between tracks, the volume knob isn’t usable at the lowest steps, and the level of detail doesn’t meet the top performing CIEMs in this category.  Even given these issues, the PP6 combines a unique sound signature with great technical performance, justifying the price and offering something different compared with other available CIEMs and systems.  The PP6 has earned ear time among my collection.


–       Excellent transparency and dynamics

–       Incredible bass performance and very natural treble

–       Soundstage is very spacious with good depth and imaging


–       Need to use external box (until the passive crossover cable is available)

–       Volume at the bottom of the pot is unusable, limiting low volume listening with fixed output sources

–       Background is not black

View the CIEM comparison list





Having a life-long love of high-quality audio and gadgets, average_joe got back in touch with his audiophile side after a hiatus caused by life. His focus became headphones and related gear as the size and price fit his life better than home audio. He believes the entire audio chain is important, and likes to continue to think past the headphone and on into the head, as he believes understanding the details of how we hear will lead to a better audio experience.


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