EarSonics S-EM6 Limited Crystal Edition

EarSonics S-EM6 Crystal Edition universal fit CIEM review


EarSonics EM4: The S-EM6 is a bit more spacious and open sounding than the more mid-forward EM4.  Overall, the S-EM6 sounds smoother, more coherent, clearer, and has better tonal accuracy.  Bass is close, but the custom fit of the EM4 provides a bit better low end with more extension and note sustainment as well as better dynamics and imaging.  Treble of the S-EM6 is a bit more linear with less harshness, but similar in detail levels.  With similar characteristics, the S-EM6 ends up being the more tonally accurate and refined of the two, but the EM4 pulls out a narrow victory based on technical performance.

EarSonics SM64:  With a very similar sound, the S-EM6 is the big brother to the SM64.  Both share a laid-back presentation in comparison with the EM4, SM3, and EM3 Pro, but the SM64 is a bit more laid back.  Both have plenty of bass that can rumble and hit hard, but the S-EM6 bass sounds more “solid” and extends deeper.  The more forward midrange of the S-EM6 has better depth, additional detail, more clarity, and is more lively and engaging.  The SM64 has a more prominent upper midrange giving a bit of a brighter sound in comparison with the smoother, more coherent and linear S-EM6.  Overall, the S-EM6 conveys more emotion and has a fuller sound that is more transparent and head-and-shoulders more cohesive.  Ultimately, the S-EM6’s superior imaging, instrument separation, and capability makes the SM64 sound a bit hollow in comparison.  Switching between the two highlighted that the S-EM6 was much more musical, making it easier to get lost within the music.

Fit Ear To Go! 334: The comparatively bass heavy and brighter 334 is more up-front in relation to the smoother, more spacious S-EM6.  Soundstage proportions are similar, but the S-EM6 images better within the soundstage and presents with more detail resulting in a higher level of resolution.  Even though the 334 is more up-front, the S-EM6 midrange is more prominent with an overall more neutral sound due to better coherence and transparency.   Dynamics are similar, but the bass enhancement of the 334 can make it seem more dynamic (especially when there is no volume matching, as the 334 is more sensitive).  While the 334 has more bass enhancement, the S-EM6 is more capable of sustaining deep bass notes.  Even though the S-EM6 has a smoother note, it is still more detailed and has better control in the bass region.  Clarity is not too far off overall, with the S-EM6 pulling ahead, which also has better focus within the soundstage.  Overall, the S-EM6 provides a smoother, more refined sound that is more expansive and laid back compared with the 334, which has more of a V-shaped sound signature that is more exciting and analytical.

AKG K3003 (reference ports): The K3003 sounds V shaped in comparison with the smoother, more neutral S-EM6.  The S-EM6 holds a clarity and instrument detail advantage from the superior imaging and presentation depth while the K3003 presents with slightly more width.  The K3003 has more bass rumble, but the quality difference in bass is significant as the S-EM6 is tighter and cleaner.  Dynamics are better with the K3003, primarily in the bass region due to the dynamic driver.  Coherence and transparency are far superior with the S-EM6, and the more linear frequency response and smoother notes sound more natural.  The S-EM6 is more forgiving of poorly mastered tracks and brings out excellent depth of presentation the K3003 misses with well mastered tracks.

Sennheiser IE800: The IE800 vs. the S-EM6 is similar to many other BA vs. dynamic driver comparisons, as both perform very well and have characteristic differences.  The IE800 is smoother, but in being so gives up detail and resolution.  Soundstage width is similar, but the S-EM6 has superior depth of presentation, making the IE800 sound a bit flat in comparison.  The S-EM6 is more mid-forward with a bit better coherence and transparency.  Tonally, the IE800’s smoother treble and more neutral bass lead to a bit more natural sound overall, but the S-EM6 is more punchy and fun while still retaining a good tonality.  The IE800 is very enjoyable, but is a bit V-shaped in comparison, although it will appeal more to fans of “neutral” while the S-EM6 presents additional information from recordings and a more engaging presentation.

Rhines Custom Monitors Stage 3: The brighter Stage 3 has a more mid-forward presentation and sharper note in comparison with the smooth and coherent S-EM6.  Soundstage proportions are different as the Stage 3 is wider than deep while the S-EM6 is deeper than wide sounding in comparison.  Focus with the soundstage is a bit better for the S-EM6, especially in the midrange, which is more prominent on the S-EM6.  While the notes of the S-EM6 are smoother, they also convey a bit more detail and the overall presentation has more resolution while being more forgiving of poor tracks.  The better coherence leads to superior transparency with the S-EM6, although the Stage 3 has better dynamics.

The bass presentation of the Stage 3 is more enhanced and forward, with more punch and reverb, however the S-EM6 sounds more neutral, controlled, and accurate in comparison.  Warmth is similar, while the midrange of the Stage 3 is a more forward overall, but recessed in relation to the bass and treble, especially when compared with the S-EM6.  Vocals on the S-EM6 stand out more and the entire presentation seems to have a better balance.  The brighter Stage 3 is more analytical in comparison with the always smooth S-EM6, even though it doesn’t give up anything in detail and is much more forgiving.

With different presentations, the S-EM6 has a smooth, coherent, and mid-leaning sound in comparison to the more analytical, V-shaped Stage 3.  Both offer spacious presentations, but in different ways as proportions differ, and the Stage 3 is more reminiscent of a reference sound, at least on the top end, while the S-EM6 is more representative of a stage monitor that is more forgiving up top.

Spiral Ear SE 5-way Reference: The more laid-back SE5 has a similar, but different presentation that has better extension at both ends compared with the more mid-centric S-EM6.  Spatially, the SE5 presents a larger space with similar proportions.  The SE5 sounds more transparent and coherent, but not by a whole lot.  Detail levels are also higher on the SE5, with better spatial queues and more resolution and recreation of ambiance.  Dynamics and clarity are superior from the SE5, as is imaging.  Note attack and decay sounds similar for the most part, but the SE5 has a wider range of capability.  The S-EM6 can be more forgiving of poor masters due to the more relaxed treble.

Bass is similar, with a slight more emphasis on the S-EM6, but the SE5 extends deeper with better capability leading to a more convincing and moving experience with bass heavy tracks.  Warmth is similar, but the S-EM6 is slightly warmer.  The midrange of the two is divergent, as the S-EM6 midrange is more pulled forward in relation to the bass and treble compared with the linear SE5.  The midrange of the S-EM6 is presented closer, which emphasizes vocals and midrange instruments but the SE5 has more presentation depth that has higher resolution within the soundstage resulting in better clarity and ambiance.  The upper midrange of the SE5 is a bit more pronounced and the treble is more extended and brighter, but the quality is similar other than the difference in detail.  While the S-EM6 treble is linear and extended, the SE5 is more extended.

The SE5 is an excellent reference monitor that is very linear, while the S-EM6 possesses many of the same qualities, although with a bit lower technical performance, and more mid-focused.  The overall tone between the two is similar and the performance is as close as I have heard from a universal fit monitor.



EarSonics S-EM6 with iBasso DX50

Portable Sources, DAPs

Sandisk Sansa Clip+: The Clip+ imparts a thicker sound on the S-EM6, but at the same time provides very good imaging and presentation depth.  Compared with the iPhone 5, there is more of a sense of space and better layering, but clarity isn’t quite as good and the Clip+ isn’t as refined or smooth.  Bass quality is a bit better and reaches slightly deeper than the iPhone 5. 4/10

Apple iPhone 5: The S-EM6 sounds OK from the iPhone 5, but it lacks presentation depth the Clip+ provides.  Dynamics are not as great and the bass presence isn’t as strong resulting in an ever so slightly brighter.  Detail levels are OK, but the layering isn’t great. 3.5/10

Hisoundaudio Nova-N3: The N3 adds a brightness to the S-EM6 that neither the iPhone 5 or Clip+ do, but the bass is still present while being closer to the iPhone 5.  Spatially, it is good and better than the Clip+, but it isn’t necessarily a large improvement.  The clarity of the presentation does give the Nova 3 an advantage, and the detail levels are slightly higher. 5/10

Fiio X3: The Fiio X3 is similar in presentation to the Nova-N3, and performance isn’t too far off between the two.  The X3 does have slightly better dynamics and a slightly more presentation depth, but the differences are small. 5.5/10

iBasso DX50: The DX50 sounds open, dynamic, and clean with the S-EM6, making the Nova-N3 and X3 sound a bit unrefined, closed-in, and dull.  The extra presentation space allows the S-EM6 to operate more to its strength, with better instrument separation and depth of presentation than other sub-$300 DAPs I have heard.  The combination of characteristics results in a sound that is quite musical. 7/10

Astell & Kern AK120: The AK120 imparts excellent depth of presentation, dynamics, and a higher level of resolution than the DX50, X3, and other sources tested.  Compared with the DX100, the performance level is quite close, only differing in space, which the DX100 wins, and clarity, which the AK120 wins.  This pairing is quite musical and enjoyable. 9/10

iBasso DX100: The DX100 adds a little bit of space and low-end capability to the S-EM6 compared with the AK120 but loses out slightly in clarity.  Overall this combination is very enjoyable, transforming track playback into a truly musical performance.  9/10


Portable Sources, DAPs with Amps

iBasso DX50 ->

Shonuyn SH-306A: The 306A sounds similar in sound signature to the DX50, but with a bit less deep bass.  The overall sound isn’t as open and the level of detail is lower on the 306A than from the headphone out of the DX50.  Not bad, but lacks the open and naturalness the DX50 provides.  5/10

Sunrise Dolphin: The Dolphin has a different tonal quality than the DX50 headphone out, with less treble and a smoother, warmer sound.  The overall space is a bit smaller than that of the DX50, but there is slightly better layering from the Dolphin.  Sound quality between the two isn’t that far apart. 7/10

Neco V2: The Neco V2 pulls the sound closer and amplifies the bass region compared with the headphone out of the DX50.  Depth of presentation is similar, as is clarity, control, and detail level.  If you have a DX50, there isn’t really a reason to add the Neco unless you want more bass. 7/10

Just Audio uHA-120: The uHA-120 gives a nice, open space, and improves the presentation at the outside edges resulting in a larger space and a more realistic sound compared with the DX50 headphone out.  There is a bit less bass and a bit less upper midrange presence for a slightly darker presentation, but the clarity is slightly better.  7.5/10

JDS Labs O2:The O2 is a bit more laid-back than the DX50 headphone out, and the sound isn’t quite as smooth or natural sounding.  Spatially, the O2 is very similar in size to the DX50 HPO even though the presentation is more laid back.  Background instruments are brought more to the front with the O2, but detail levels are similar.  6.5/10

Tube Amp TA-1: The TA-1 has a similar presentation to the DX50 from a size and space perspective, but the overall sound is more refined with better layering while the bass is more powerful with excellent control.  Tonally, the TA-1 sounds a bit more natural, especially with female vocals.  8/10

Headstage Arrow 12HE 4G: The 4G adds space to the presentation compared with the headphone out of the DX50, but the 4G brings out a harshness to the upper midrange that can lead to slight sibilance.  Bass is more authoritative and controlled with the 4G, and overall dynamics are better, but the DX50 headphone output sounds more natural. 6/10

Headamp Pico Slim: The PS has a bit more laid-back midrange and better presentation depth, but the width is similar.  While the sound is good, it is a bit on the digital sounding side in direct comparison with the DX50 headphone out. 6.5/10

Leckerton UHA-6S MKII: The 6S sounds more open, lively, and natural compared with the DX50 headphones out.  There is a musical attribute that is added from the 6S that the DX50 is missing. Bass is a bit deeper with the 6S with more reverb and better punch. 8/10

Lear FSM-02 V2 Class A: The FSM-02 V2 has a more open, natural, and refined sound compared with the DX50 headphone out.  Layering is superior while retaining smoothness for a musicality that makes the DX50 sound digital.  9/10

Portaphile 627: The 627 takes the great things the FSM-02 V2 does and improves upon them, with an even smoother, more musical presentation.  Control is excellent, spatial qualities are great, and tonal quality is excellent with both male and female vocals.  The S-EM6 really shines with the 627.  10/10

Source Summary: The S-EM6 benefits from both a better DAC and a better amp, and both are needed to get top performance.  The DAC will recreate the spatial qualities the S-EM6 can recreate in a realistic way while the amp will enable control and make sure the spatial qualities decoded by the DAC are realized.  Today’s top portable DAPs will pair well with the S-EM6 while a phone or lower cost media player will not push the S-EM6 to its full potential.  While not all amps showed improvement vs. a mid-level DAP, they can help some lower end sources perform better.

EarSonics S-EM6 Limited Crystal Edition


The EarSonics S-EM6 Crystal offers a very musical, coherent, and transparent sound that emphasizes the midrange while offering strong performance across the spectrum.  The presentation is large with excellent proportions and fantastic imaging within the soundstage, recreating ambiance few headphones can.  Performance is at the top of the EarSonics product I have heard, and the signature is truly in the EarSonics mold, but better.  If you like a focus on the midrange and want to get lost in your music, the S-EM6 can help you accomplish that.  Just be ready to pair it with a good source chain to realize the potential.  Side effects include loss of sleep due to being mesmerized by music you didn’t know could sound so good!

–       Exceptional transparency and coherence across the frequency spectrum and soundstage presentation
–       Balance between capability and presenting with the right emphasis
–       Universal fit custom can be heard by all

–       The shell is large and the canal shape may be problematic for some
–       Sound changes significantly depending on ear tips, and only one size of ear tips are included.  If other ear tips are used, it can change the sound signature and performance.

View the custom in-ear monitor chart (note, you must select the “Show other types of headphones for reference” box and click search for the S-EM6 to appear)





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.


18 Responses

  1. Hi Joe,

    I have 2 questions, one not so related to this review.

    1. I’ve seen contrasting reviews on the S-EM6. Some say it is really dark or ‘woolly’ such that detail retrieval is way below its price range. Some others, including yours, say the treble, while not bright, is still linear, smooth and detailed. What are your thoughts on this?

    2. Are the images in THL website supposed to be automatically downloaded when clicked (instead of enlarge)? It is kind of annoying imo.

    And as always, thanks for your awesome reviews!

  2. Hi,

    first off thanks for the review.
    Considering that you have reviewed this IEM and a fair share of cable, what cables do you think would go along very well with the S-EM6?

    Best regards.

  3. Thanks for reading! I have not yet heard the LCD-3, just the LCD-2. EarSonics products have a similar sound signature, but with a bit more mid-centric sound vs. mid-forward. The difference is mid-forward is when the entire presentation is from an up-close perspective while mid-centric is when the midrange is a bit more forward than the rest of the spectrum, highlighting the mids and vocals.

    I do think people that like Audeze sound will most likely like EarSonics sound. Also, please remember that there are inherent differences between headphones and CIEMs, with headphones having a larger overall presentation that is more out of the head while CIEMs typically are more detailed and have better imaging.

  4. Great review. I want to ask , I heard lcd 3 sound and like it too much and bought one . In your experience are there any ciems or iems near the sound of Lcd 3?

  5. Sounds like a plan. Let me know your thoughts when each component arrives, especially the S-EM6. That is a whole new level compared with the SM3!

  6. So I took your advice and decided to do this step by step. Just picked up the DX50 and will get the S-EM6 in a couple of months time. Thanks for the help.

  7. I would say the S-EM6 is your best bet, especially since it is the top-performing universal I have heard in addition to having the sound signature you are looking for.

  8. Just one last question from me. I listen to a variety of genres ranging from jazz to dubstep to orchestral music. Given this, would the S-EM6 continue to be the best bet or is there something else that you would suggest as a good a combination of being non-fatiguing, forgiving and a good all rounder? I’m only looking at Universals right now and not considering customs

  9. Thank you for the replies. I did indeed miss that there was a second page to this review, checking it out now.

  10. The Westone UM3X is similar but different. The differences to my ears are that the UM3X has a much smaller overall soundstage size, but there is much debate about that comparison. The UM3X also has a bit different tonal balance, and it is usually a one-or-the-other type love-hate relationship.

    Once you get above a certain level, many of my collection of CIEMs becomes very enveloping, but they still don’t have the same midrange qualities of the S-EM6. Some examples of enveloping CIEMs include the Rhines Custom Monitors Stage 3, Spiral Ear SE 5-way Reference, Fit Ear PS-5, and M-Fidelity SA-43.

    Another is the Custom Art Music One, and the Harmony 8 might have a similar sound signature, but I haven’t heard it.

    As far as the 846 and 334 v the EarSonics, I do have the 334 compared with the S-EM6 on page 2 of this review. The 846 is good but different, and doesn’t quite stand up to the S-EM6 IMO.

  11. My comparative write-ups are on page 2 of this review, if you missed them. The SM-64 and S-EM-6 are both a bit more laid-back than the SM3, but still have the EarSonics flavor due to the midrange in relation to the bass and treble. So many other sound signatures are opposite or go for neutral. Something close, but not quite the same is the Perfect Seal PS6, which is quite good for $650.

    As far as the SM3 vs. the S-EM6, it is like pitting a good but not great high school athlete vs. a pro. The S-EM6 makes the SM3 sound quite bad IMO. Sure, the signature isn’t the same, as it is more spacious, but due to the higher performance, it is more enveloping and involving.

  12. And one more thing I’d like to add is – have you encountered any other IEM with a similar enveloping presentation to the SM3. That is something that really appeals to me and the change from that is why I never considered the SM64 in the past. Is the S-EM6 similar in that regard?

    And what are your thoughts individually on the 846 and TG334 and how would you describe them in comparison to the SM3 and the S-EM6? Thanks again.

  13. Thanks for the detailed response. I have been leaning towards looking at upgrading the source as well but I’ll do it in a staggered fashion starting with the IEMs and then adding the DAC/Amp.

    You pretty much have me sold on the S-EM6 because I don’t think I’ll be able to enjoy anything else without the wonderful ES sound signature and midrange. One last question, how is the SM64 as an intermediate step between the SM3 and the S-EM6? I heard the signature was slightly different for that so I never tried it. Thanks again.

  14. Hi AV,

    Thanks for the question. The S-EM6 is a natural progression to the SM3, and the EarSonic sound signature is different than the others. The midrange area of the S-EM6 is something to behold and something that grabbed me without lacking anywhere else; the others, while good, don’t have the same characteristics.

    I have not heard the Primo 8, so I can’t say anything about that, but the reports are that it performs about as indicated by the price point. If you want great price for performance, the Perfect Seal line is quite good with a somewhat similar sound signature, but it too won’t have the vocal magic of EarSonics.

    Most IEMs benefit from a better source, and typically higher driver count CIEMs benefit more. You will be leaving something on the table in all cases, but you will be leaving more potential untapped with a higher performer as there is further up to go from the limitations of the source. It may be worth getting an external Android amp/DAC for whatever you get. I am trying out the ADL X1, which improves my iPhone output a good amount.

    Let me know if you have any other questions.



  15. Hi Joe,

    I’d asked you for advice on head-fi before picking up the SM3 some 3 years ago and I’m glad I did because it still is my favourite IEM (having listened to nearly everything at the same level from Shure, Sennheiser, Westone since then). I’m looking to upgrade now and was wondering what you would suggest as an upgrade with a similar sound signature. I can’t decide between the SE846, the S-EM6 and the TG334. I think the S-EM6 is likely going to be the hardest to drive for a portable device (Wolfson Galaxy S3). I have auditioned the SE846 and found it to be better in some ways but something just felt off compared to the kind of smooth lush sound I like from the SM3. I’d still like to know what you’d recommend to someone looking to upgrade from the SM3 and looking for an upgrade. Thanks!


    PS. What do you think of the NuForce Primo8 as a smaller step up?

  16. Hi,

    Thanks for the question. I have added the Fiio X3 and iBasso DX50 to the SM64 review here. It is close, but doesn’t quite make it to 7.



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