Custom Art Harmony 8 Pro silicone shelled custom in-ear monitor review



Spiral Ear SE 5-way Reference: The SE5 and H8P sound signatures are quite different with the SE5 being more organic, warmer, and spacious in comparison to the H8P’s brighter, more analytical sound.  Spatially, the SE5 has a wider, more open sound due to the more laid-back presentation perspective, but the overall size of the SE5 isn’t that much larger.  Notes are different, but are very capable on both, with the H8P having a faster average attack and the SE5 having a longer sustain in general.  Detail levels and resolution are very similar, but the H8P articulates the details more while the listener has to search for the detail with the SE5.  Both have exceptional coherence, punch and dynamics, and share a high level of overall transparency; however, the SE5 is more forgiving of poor quality treble.

Both are capable in the bass department, but the SE5 bass has more body in general and a bit slower note which leads to a sense of more bass.  The H8P is tighter and cleaner overall, and while the SE5 recreates more texturing within the note, the H8P reveals more detail and sounds more precise.  Mid-bass is close between the two but the SE5 sounds warmer due to the differences in the higher registers and the slightly thicker SE5 notes.  Differences in the upper midrange are significant, as the SE5 is more laid-back for a very different presentation perspective.  Treble is also quite different as the SE5 is laid-back yet present while the H8P is more forward and brings the details to the forefront; however the SE5 treble has a more natural ADSR.

The Spiral Ear SE 5-way Reference offers a more laid-back sound that is organic and easier on the ears, but doesn’t present detail in an articulated, upfront way like the brighter Custom Art Harmony 8 Pro.  Performance is similar in many ways, but these two are good compliments vs true competitors due to the sound signature differences.


Hidition NT-6 Pro: The H8P and NT6P have similar sound signatures, but the H8P is a bit brighter in comparison with the bass and treble enhanced NT6P.  Spatially, the NT6P has a wider presentation that is not far off in presentation depth, but has a more precise focus within the soundstage.  Detail levels of the NT6P are about the same, but the NT6P articulates the details quite a bit more, and when combined with the slightly quicker notes and enhancements at both frequency extremes, the difference sounds significant.  Dynamics are quite similar, and the NT6P holds a slight edge in imaging and clarity while the H8P slightly outperforms in coherence and overall note ADSR.

With a good deal more bass presence in the deepest registers, the NT6P has similar note sustainment capability, but the H8P slightly outperforms.  Quality of the NT6P is a bit higher however, with slightly better control.  The added bass presence of the NT6P gives it a more authoritative bass sound and the perception of more warmth at times.  The midranges are similar, but the NT6P presents from a slightly further back perspective and has a bit cleaner midrange in part due to the perspective and in part due to the better focus.  The upper midrange and lower treble are quite similar while the treble of the NT6P brings more detail to the forefront with enhancement.  Quality of the treble is superior from the NT6P as the H8P gets a bit harsh with MP3 tracks vs. FLAC, and doesn’t have quite the natural sound.

These two are similar, but the Hidition NT-6 Pro offers a more colored albeit exciting sound that is overall a bit clearer and more articulate.  The Custom Art Harmony 8 Pro is more neutral and a bit more up-front with performance that is similar.  The choice between the two should come down to where you order from, what shell type you want, and if you like your deep bass and high treble enhanced.


Hidition NT-6: The H8P and NT-6 are quite similar in both presentation and frequency response, but there are subtle differences.  Spatially, the two are extremely similar in both presentation perspective and spatial size, but the slightly more forward NT-6 can project sounds further in all directions and has a slightly better focus within the soundstage.  Notes of the H8P are slightly thicker in general with the exception of the treble, where the notes have a shorter decay leading to a sharper note.  Detail levels, resolution within the soundstage, transparency, and coherence of the H8P are all slightly better than the NT-6 while dynamics are similar and clarity and imaging of the NT-6 win out.

The deep bass of the NT-6 is more prominent and the overall sound is warmer while capability and control are a bit better with the H8P.  The midrange is similar, but there are differences in the upper midrange area, with the NT-6 having slightly more emphasis that pushes the presentation a bit forward.  The treble of the NT-6 is slightly more prominent but the quality is better, with a more natural note decay making the NT-6 more forgiving, especially with MP3 tracks.

The Hidition NT-6 and Custom Art Harmony 8 Pro have very similar sound signatures, but there are significant differences.  The NT-6 has more emphasis on both ends of the spectrum, an overall brighter sound from the more forward upper midrange, better clarity, and a smoother treble region while the more detailed and transparent H8P has a more neutral feel overall due to the less aggressive upper midrange and flatter frequency response but, the treble has a sharpness the NT-6 doesn’t.


Ultimate Ears Personal Reference Monitor: The Personal Reference Monitor (PRM) has a warmer, more laid-back sound in comparison to the brighter Harmony 8 Pro (H8P).  The PRM has a wider presentation, but the H8P sounds more open and has better soundstage proportions with a bit more presentation depth while imaging is similar.  Notes ADSR of the H8P are a bit quicker, but better controlled leading to a sharper focus of the presentation resulting in superior clarity for the H8P.  Dynamics and punch are also superior on the H8P while transparency and coherence are close.  The H8P presents with slightly more detail with better articulation and the spatial queues within the soundstage are slightly greater.

Bass quantity of the PRM is slightly higher than that of the H8P, although the bass of the PRM can be tuned to your liking before you take delivery.  Quality and capability of the H8P are both superior in the bass region, especially the ability of the H8P to sustain deep bass notes, which is a significant difference.  The midrange presentations are quite different as the H8P is more forward but has a slight advantage in depth of presentation.  Tonal qualities of the PRM sound more accurate, especially with female vocals as the brighter H8P sounds like it adds emphasis that the PRM doesn’t.  There is a small bump from the PRM, but the H8P has more emphasis in the upper ranges.  Quality of the PRM treble is slightly smoother and more forgiving than that of the H8P, although the H8P is more detailed in the treble region.

These two are quite different in overall tonality and really aren’t competitors.  The H8P is more capable overall, but has a brighter tonality while the PRM sounds more true to life, and you can tune the Personal Reference Monitor to your liking before you buy.  The H8P does offer more detail and a more forward sound if you want to hear everything in your music.

[divider][sneak peek]EarSonics EM32: The EM32 and H8P share a similar presentation perspective, but just about everything else is different.  Spatially, the H8P sounds more open although and a little bit more laid-back while imaging is similar with the EM32 having a slight advantage.  Note ADSR is similar in capability, but the midrange and bass of the EM32 have a bit slower response overall while the treble performance is quite similar.  Detail levels are higher on the H8P, as is clarity.  Dynamics are similar as is transparency and coherence.

The EM32 is tuned to pump out the bass with a significantly higher quantity than the H8P, and while the EM32 has much more rumble and note sustainment, the H8P has much better control and quality.  The EM32 is slightly warmer, which is in part due to a slightly thicker note.  The midranges aren’t too far apart in presentation, but the EM32 has a bit larger space but not as much depth relative to width, pushing the midrange a bit closer than the H8P.  Layering is very good with both, but the H8P sounds leaner and clearer through the midrange.  Upper midrange and treble is boosted in the H8P in comparison with the EM32, but quality is quite close, with the EM32 slightly edging out the H8P.

Both the EarSonics EM32 and Custom Art Harmony 8 Pro offer excellent performance and something different.  The EM32 provides a warmer tonality and more bass quantity and sustainment with a focus while the H8P offers more detail articulation and a thinner, brighter sound.  These different flavors are complementary and can co-exist in a collection, or stand alone and offer plenty of pleasing sound.


Hidition Viento-R: The Viento-R is closest to the brighter H8P with both switches in the down position.  Spatially, the VR has a bit closer presentation perspective but a larger overall soundstage size that shows with very spacious tracks, but the H8P has a bit better width to depth proportions.  The VR has better focus within the soundstage, and while both offer great clarity, the razor sharp focus of the VR gives it the nod.  Detail levels, resolution, and dynamics are slightly better with the H8P while the VR images better and coherence, transparency, and articulation of details are all close.  Notes of the VR are a bit more natural with a bit longer average sustain than the H8P and the ADSR of the VR is slightly more capable.

Bass quantity of the VR is slightly higher, but the H8P has more note sustainment capability resulting in very bass heavy tracks having more emphasis.  The VR is a bit warmer, and while the midranges are similar, the VR offers a clearer window into the music and a more natural note, but tonality of vocals on the H8P are a bit more realistic.  The upper midrange and treble of the H8P are more emphasized resulting in a brighter overall tonality, but the biggest difference comes in the note smoothness, as the VR is quite a bit smoother and much more forgiving while retaining nearly the same level of detail.

These two competitors offer similar but different sound signatures and strengths.  The silicone shelled Custom Art Harmony 8 Pro from Poland is bright and more analytical with a very neutral presentation, exceptional capability, and great tonality.  The Korean Hidition Viento-R also offers a presentation that is on the analytical side, but has a more natural treble note, and when combined with the extremely clear sound, it conveys detail in a polite way.  Switches on the VR give it an advantage if you want to be able to adjust the sound.  Both offer something special making choice between the two difficult.


Custom Art Music One: Comparing the single driver from Custom Art to their 8-driver flagship is more about sound signature and what once gets with an upgrade than a true comparison.  The H8P has a fuller bottom end, brighter and more analytical top end, better depth of presentation and space, layering, and a more laid-back overall presentation, which is of no surprise considering the design and price difference.  While there are differences in presentation, it is easy to tell these were both designed by the same company as there are similarities in the midrange and despite the brighter sound of the H8P, tonality and balance are reminiscent of each other.

Technically, there is a very large gap that gets smaller as the source equipment improves, but even with the best source I have there is still a significant gap.  The MO is more forgiving and the top end is in general smoother, especially with less than stellar recordings, but the H8P adds layering and detail the MO misses.


Portable Sources, DAPs

Sandisk Sansa Clip+: The Clip+ pairing with the Harmony 8 Pro is less than ideal as the Clip+ doesn’t push the bass drivers well and the analytical nature of the treble is emphasized.  Also, the 3D aspects of the H8P are not realized with the Clip+.  The iPhone 5 is smoother in the treble and has much better bass response, but it doesn’t sound quite as precise. 2/10

Apple iPhone 5: The iPhone 5 is a decent pair with the Harmony 8 Pro, but not great nor something I would recommend.  The pairing, while not offensive or lacking like the Clip+ at the frequency limits, holds the H8P back as it isn’t as clear or precise nor does it have the presentation space like it can be with better sources.  It will get by for those that carry light, but far from ideal. 3/10

Fiio X3: The Fiio X3 pairs well with the Harmony 8 Pro to recreate an airy, 3D, dynamic, and accurate sound that is very transparent to each individual track.  In comparison with the iBasso DX50, the treble is a bit more prominent and better articulated while the overall sound is more dynamic and 3D.  7/10

iBasso DX50: The DX50 pairs better with the Harmony 8 Pro than the iPhone 5 and Clip+, but not quite to the level of the Fiio X3, which sound a bit more 3D and dynamic, resulting in the DX50 being a bit dull in comparison.  While the source is a decent match, if you don’t already have one, there are better matches for the H8P in the price range. 6/10

iBasso DX90: With good spatial qualities and a punchy, dynamic sound, the DX90 outpaces the DX50 and is a bit more detailed than the Fiio X3, with better resolution within the soundstage.  8/10

iBasso DX100: This pairing is quite revealing and transparent, displaying high levels of detail both in instruments and in the surrounding atmosphere.  There is plenty of deep bass power and punch across the frequency spectrum.  Spatial qualities are excellent and show off the exceptional soundstage proportions of the Harmony 8 Pro. 9/10


Portable Sources, DAPs with Amps

iBasso DX100 ->

Tube Amp TA-1: Since the TA-1 offers a sound on the warmer side of the spectrum, I wanted to see how it performed with the Harmony 8 Pro.  While the sound is warmer, it was also pushed a bit forward and the TA-1 didn’t match the control the DX100 internal amp and the overall sound wasn’t as concise and clean.  The treble was a bit tamed, with a softer edge to notes.  The main reason to use the TA-1 is for the warmer presentation with a smoother treble region, even if you give up a bit compared with the DX100 headphone output. 7.5/10

Lear FSM-02 V2: Comparing the FSM-02 V2 to the headphone out of the DX100 resulted in added dynamics and punch from the Class A output of the FSM, with better control over the Harmony 8 Pro.  Spatially, the HPO and FSM are about the same.  If you want better dynamics from the already dynamic H8P, the FSM will get you more. 9.5/10

Furutech ADL X1: The X1 is a good pairing for the Harmony 8 Pro, but it doesn’t offer any upgrade over the headphone output of the DX100, which is either a testament to the transparency of the X1 or the ease of driving the H8P. There is a very slight hiss from the amp with the Harmony 8 Pro.  9/10

Portaphile Micro with MUSE2 op amps: Feeding the Micro with the DX100 expecting an improvement with the easier to drive Harmony 8 Pro is asking a lot, but the Micro delivered with a more 3D and spacious presentation and a slightly better focused presentation that sounded more accurate and involving.  While the differences are subtle, they add another layer to the realism that gets recreated. 10/10

Portaphile 627: The 627 adds a bit of space to the headphone output of the DX100, but the imaging isn’t quite as good, balancing out the advantage of both.  Bass of the 627 is slightly stronger, but the tonal qualities are the same. 9/10


Source Summary: The Harmony 8 Pro is on the easier side to drive, although a mid-range digital audio player can really raise the performance.  Moving up to top-tier sources does improve the sound quality, but the amps don’t offer much improvement above a high-end DAP.  The H8P is capable to reveal details recreated by better DACs, and the more transparent the source, the better the result.


Custom Art Harmony 8 Pro 14


The Custom Art Harmony 8 Pro is an exceptional custom in-ear monitor that competes with other top of the line CIEMs, but offers a different flavor.  The 8 drivers are tuned well resulting in a clean, clear, detailed, and precise presentation that remains musical.  Sound is tonally on the brighter side, and bass is very capable but not emphasized for a sound tuned for the purist.  Performance is in line with the best of the best custom in-ear monitors for a very engaging and realistic performance that is rare in portable audio.  For those that want a lighter, detailed, and very capable presentation, the Custom Art Harmony 8 Pro is hard to beat.

– Ultra-high resolution bass sets a new standard for bass control and the ability to resolve micro-details and nuances within notes
– Overall performance makes the Harmony 8 Pro a top of the line performer

– Treble notes are a bit on the analytical side

View the Custom Art Harmony 8 Pro in the Custom In-Ear Monitor Review List

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About Author

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.


  1. average_joe. Thank you for this excellent review.
    Sometimes I sit back with a bowl of chow and read your reviews, instead of watching a movie or any TV serial.


    I’m finding it difficult to find downsides to silicone. Does it get sweaty upon extended use?
    Perhaps the art options aren’t diverse, but that isn’t a con really.

    I don’t think there are other CIEMs that use full range drivers, are there?

    • Thanks for reading, and I am glad my reviews can replace movies and TV!

      Let’s see…downsides of silicone:
      – The shells should be removed by the shell while with my acrylic shells I just twist out using the protruding cable
      – If you drop the shell, silicone bounces and can temporarily deform, but I am not sure that is a true issue vs. acrylic
      – From what I have been told but haven’t experienced is silicone is more prone to moisture related issues, although it may be a specific manufacturer (see ACS); hearing aid dryers are recommended

      There are pluses and minuses to everything depending on how you look at things. While I like silicone shells, I really can say I don’t have a preference. My preference is for an excellent fit.

  2. Hi,

    I hope you can expand a bit more on the fit issue of a silicon custom like this versus the more traditional acrylic. With its longer canal and silicon bring more sticky than acrylic, would insertion and removal be more difficult and would you be more conscious of the deeper insertion. Thanks.

    • Hi George,

      First, I have experienced several different finishes on silicone shelled CIEMs, with some being more sticky than others. Regardless, if they are sticky at first, ear lubrication and repeated use will result in easy to insert and remove CIEMs. Because silicone shelled CIEMs aren’t rigid like acrylic shells, they are more forgiving, but both should have a proper fit for ideal seal and comfort. I have also had deep insertion acrylic (Heir Audio 8.A), and silicone is certainly easier to insert and remove. Let me know if you have any additional questions.



  3. Hi…
    a great and deep review as always… congrats…
    especially for these CIEMs which are quite difficult to be tested and reviewed I think… but you gave me anyway a clear overview on a sound signature perspective…
    However, I think the CIEMs world is still too expensive… at least for my pockets so far..
    A nice 1st review for this new 2015..
    Cheers W

    • Hi William,

      Thanks for reading the review and commenting! There are many lower cost CIEMs from Custom Art and others that offer excellent value for money. If the lower cost stuff is still out of your price range, joker’s in-ear earphone review list should help with finding gems in any budget, and he and I pretty much always agree on the sound signatures and level of sound quality.



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