Preamble With CCA A10 & TRN X6 finally arrived and settled/burned in, I put together a comparison that hopefully may be of use to Head-Fi members, from whom I learned so much. It also gave me an opportunity to systematically revisit IEMs that I have collected over the last few years. The primary focus is multi-BA IEMs, mostly in $50 range, in line with my sonic and budgetary preferences. In lieu of disclaimer All IEMs were purchased at full cost from different vendors (AE, E-Bay, Amazon, etc.), so I share my absolutely unbiased and unrestrictedly subjective personal impressions. List of compared IEMs with abbreviations used Primary reviewed IEMs – A10 (CCA A10) & X6 (TRN X6) Main comparison – C16 (CCA C16), AS10 (KZ AS10) & BA10 (KZ BA10) Other IEMs used for comparison: AS6 (KZ AS6), C10 (CCA C10), ZS10 (KZ ZS10), 1MT (1 More Triple Driver), 1MQ (1 More Quad Driver), F9P (Fiio F9 Pro) CA4 (CCA CA4), ZSN (KZ ZSN, cyan & purple), DT6 (S…r DT6) GT600P (Macaw GT600s Pro), FH1 (FiioFH1), E3000 (Final E3000) Relevant info about my listening preferences I listen mostly to classical music, especially strings. I also enjoy organ, clarinet and marimba. Most important for me is how close the IEM sound to live instruments. While the perfection in this endeavour is understandably hardly attainable, I enjoy different reasonable implementations and approximations, largely looking for the resolution and timbre. I listen at moderate volume levels. I have no strong preference for prominent bass. I am not adverse to treble. At the same time, I am reasonably OK with its diminished (‘gently rolled off”) forms, as long as the resolution is reasonably preserved, as with AS10. My HiFi journey started few years ago with Fiio Q1. The next defining IEM revelation for me was 1MT, which firmly set my subjective preference to balanced armature (BA) drivers: first in hybrids and later in all-BA IEMs. The latter are consequently the main focus of this review. Other than few (Final E3000 and Sony MDR-XB50AP), all IEMs in my collection are “Chi-Fi”, given my self-imposed price-range limitation of under $150 and propensity to explore new things and different IEM signatures. My first KZ “encounter” was ZS10, which was not exactly to my liking but made me appreciate KZ. Shortly after, AS10 really became a great bingo for my listening preferences, and also brought me to join this great HiFi community. Currently, I enjoy the resolution and sound of C16, as my primary IEM for the last couple of months, while often getting back to warmer and cozy AS10. I also appreciate BA10 (other than its fit and sharp edges). So far, I have collected all CCAs out there and quite happy with their sound and diversity, so I plan to further experience at least a couple more of their future products (CCA C20(?!?)). Hopefully, trying to confine myself to CCA can reasonably limit the wallet drain inevitably associated with this hobby. Along the lines above, getting A10 was a logical choice, as the most recent CAA IEM and seemingly a close analogue of my favourite AS10, while X6 was an attempt to explore “outside of the box”. My interest in X6 was first propelled by its relatively high impedance of 58 Ohm (and the fact that using impedance adapters with AS10 was quite instructive), as well as the curiosity how the mid-centered emphasis can work out for my tastes. Finally, seeing a slew of “cautious” reviews sealed my “contrarian” decision to give it a try. I do not use equalizers, since I am biased that they cannot add what is physically missing in the IEM sound signature, but rather suppress the less wanted/needed frequencies with the negative effects on the natural balance and overtones/timbre. Music used for IEM comparison (Flac files, mostly 16/44.1, some 96/24 and 192/24) Beethoven Late String Quartets by TakacsQuartet, 4708492 Intimate Voices, String Quartets, E4775960 Brahms & Mozart Clarinet Quintets, E4596412 Schubert: Octet in F Major, D803, ONYX4006 Victoria Mullova plays 20th Century Concertos, E4757457 Sibelius - Violin Concerto (Kavakos), BISCD500 Stravinsky: The Rite of Spring & other works for two pianos four hands: Marc-André Hamelin (piano), Leif Ove Andsnes (piano), CDA68189 The Very Best of Leif Ove Andsnes, 0947872 Komitas: Seven Songs (Piano), 4812556 Beethoven: Missa Solemnis, 4297792 Sibelius: Symphonies 4 & 7 (Karajan), 4395272 Sibelius: Complete Symphonic Poems, 9212 Veljo Tormis Forgotten Peoples, 4342752 Veljo Tormis Works for Men’s Voices TOCC0073 Bach Beat: A Marimbist as Pointillist, AMR1044 Marimba Crystal, 4538182678398 Alain Kremski: Music for Singing Bowls and Gongs, CDX69705 Brahms – Complete Organ Works, NI5262 Poulenc: Organ Concerto, different recordings MAGIC! Peter Richard Conte. The Wanamaker Grand Court Organ, G-49248 Bach: The Art of Fugue, BWV1080, E4672672 & E4776508 For the comparison of the bass, organ music, especially WGC with its claims of preserving the lowest bass frequencies, was used. Treble was evaluated with the violin and percussion music. Orchestral music was used to compare resolution, and chamber music (especially string quartets and piano duets) ─ to compare balance and timbre. Sources: Pioneer XDP 30R with a balanced output and low gain was used as a primary source. Some comparisons using Fiio Q1-II and Samsung S9 were also made. IEM tips Most definitely, tips matter a lot for the sound and tight fit affecting the sound. “Rolling” through several different styles and sizes, my evolution brought me to wide-bore tips. My simple view is that when the tip bore is larger than the nozzle opening – nothing is constraining sound propagation, and all the sound is delivered least perturbed to the ear. I mostly use JVC Spiral Dots to listen to music and for this comparison. Other wide-bore generic tips work reasonably as well. KZ starlines feel quite OK for several KZs and CCAs. At the same time, Spinfit (CP100) tips are noticeably restricting the sound to my ears. Cables My listening experience so far is that cables only matter when their resistance is a sizeable fraction of the IEM resistance (along the 1/16 guide) or in a case of the impedance mismatch between the source and IEM. I got a couple of budget (~$25) 8- and 16-core cables that I enjoy aesthetically and for their practical convenience (less tangling, better fit around the ears). With my equipment and my ears I do not perceive a noticeable difference in sound using these cables compared to simple original KZ cables (ZS10 & AS10 generation and newer). At the same time, impedance adapters do make a noticeable difference to my ears (both positive and negative) by making the source functioning more (or less) optimally with IEMs. I tried to use the same NiceHCK 8-core balanced cable (2.5 mm) for all comparisons, wherever possible. “Burning in” In my experience, 10-20 hours of play time was often making a noticeable difference. All IEMs were played at least 20 hours prior to the comparison, with minimal further changes in sound perceived. (If more hours are needed, I strongly feel that it should become the responsibility of the manufacturer to deliver IEMs to customers close to their optimal state; I personally prefer not to buy green tomatoes unless for some special purposes). For the “burning” I simply play the music that I am listening to, sometimes using slightly higher volumes. Summary of the technical characteristics of the primary compared IEMs [The fully formatted table is included in the attached .pdf file] IEM Drivers Impedance Sensitivity Weight TRN X6 6 BAs per side: 2×31602 +2×30018+ 2×30095 58 Ω 96 dB/mW 4.0 g CCA A10 5 BAs per side: 22955 +2×29689 + 2×30095 15 Ω 98 dB/mW 8.6 g KZ AS10 5 BAs per side 22955 +29689+31005 +2×30095 14 Ω 105 dB/mW 4.8 g KZ BA10 5 BAs per side 22955 +29689+31005 +2×30095 14 Ω 105 dB/mW 6.3 g CCA C16 8 BAs per side: 2×22955 +2×29689 +4×30095 27 Ω 105 dB/mW 9.2 g I thought that it will be efficient to describe all IEMs one by one, with more emphasis on the newer and then the primary comparison, with a reasonably concise description for the rest. TRN X6 (X6) The package is OK, it does not bother to inform of the usual info such as frequency range and sensitivity, at least in English. It duly informs that it is a “reference grade in-ear monitor”. Sure! X6 visual appearance is OK, but the design and its implementation made a rather negative impression on me. The moulded plastic is far from perfect, some visual boundaries of 3-D printing (or moulding) look a bit like cracks. Tips notoriously do not fit well, with the tips provided in the package literally jumping out by themselves from one of the earpieces, while those that stay (that one needs to find carefully) have a tendency to remain in ears. One of my earpieces also does not have a good snug-fit of the cable connection, being semi-loose. All my previous experience with 2-pin connectors was KZ/CCA that did not give me a single problem, since their design is simple – placing the connector (their “B-type”) in an opening of a shell. The design of X6 has the connector embedded into the resin of the shell and the fit relies on the ridges of the moulded shell, which does not work well in combination with the shrinkage upon polymerization. Not only poor QC, but not a reliable design first of all, in my opinion. The fit is really nice for me, it is just a bit small to work perfectly, but is one of the most confortable IEMs that I experienced together with CA4 & C10 and Fiio FH1; AS10 being close. The sound literally “needs to get used to” and requires some match in listening preferences. First, the lows and highs feel limited, being sacrificed for the mids (anti V-shape, “Lambda” (?)). Second it does not work for all music to my ears. Most music with the extended treble feels “off”. In particular, violin music does not sound natural. In the worst case, it feels like the music was recorded with a voice recorder (with a very good resolution, but the emphasis on mid/vocal range). I do not listen to female vocals, so I can’t comment much about it. For male vocals, it can work well. So, when the music fits to X6 capabilities, it can really shine. The bass is OK for me – it is there “when called for” (some may feel that you have to call first); mids are well-resolved with some overemphasis on higher mids. This feels to help resolution and coherence when not too much treble is present. But when the treble is strong – everything feels off, kind of a dissected timber. Surprisingly, I did not feel any “special effect” of a relatively high-impedance of X6. The sensitivity is OK, only a bit lower than other compared IEMs, but it did not feel “hard to drive” at all. I can hardly recommend X6 as one’s first or second BA IEMs. To some extent, it can be called an antipode of DT6 – minimal lows, highs are not its strengths, the timbre may feel distorted… But then in some music it can shine: clarinet (not with altissimo), trumpet (yes, I have to totally agree that it suits listening to Mile Davis with his unique sound) and saxophones (at least alto and tenor. So as a special-purpose IEM or fitting to one’s listening preferences, it may work quite well. CCA A10 (A10) Not much surprises with the package, design and appearance. The shell features a lot of similarities with previous KZ/CCA models. I am personally quite fine with it – if it works well for fit and perhaps acoustics - why invent something else, like BA10. The top plate is virtually the same as C16, but intensely blue coloured (I am OK with it, as well as “the large 5”, but to my preferences, a simple and functional design of CA4 is the most appealing). Compared to X6, it can be appreciated how neater the internals are organized and implemented. Compared to C16, the aluminum nozzles are definitely a nice functional feature (tips barely stay on a plastic nozzle of C16, AS10 and AS06). The new C-type connector is surely nice and sturdy, but I never had any problems with the B-type in KZ/CCA and am not particular fond of the idea of getting new cables, especially since I am mostly using balanced ones; while “type B” cable fits somewhat reasonably into “type C” IEM connectors, the opposite is not the case at all. My hopes for A10 was to get something similar to AS10 (wilder hopes were for ZS10 pro-like vs. ZS10 applied to AS10). Then, AS10 is a really nice fit for my subjective sound preferences, and A10 is not exactly there, but not by any means is totally off either. A10 largely felt more as a little brother of C16 with a similar sound signature, but less BAs, so the resolution is less, less mids, a bit less bass (1/5 is less than 2/8) and correspondingly more prominent treble. In some sense, it can be thought of a hybrid of C16 and BA10. Putting together this comparison helped me realized this. The A10 treble is just right for me on an upper boundary of my preference spectrum. I really like how some violin recordings sound with A10 (I used to use F9P to this music occasionally). Now A10 will likely replace F9P. I’ve tried Fiio Q1-II with AS10. I largely use Q1-II as an amplifier with my DAP, since I feel the amplification is the best part of it. Q1-II feels making signal smoother, while more constrained as well. Q1-II is really more helpful as an amplifier or DAC with smartphones. It really surprised me that A10 sounds very dry and not pleasant with the 20-Ohm adapter. By comparison, AS10 starts to sound more analytical, but rather showing new facets than being unpleasant. A different crossover design, perhaps. Similar to AS10, the background noise is more noticeable with A10 due to its low impedance. Overall, A10 made a good impression as a good logical step in the development of AS10, BA10 and C16 in the direction of more treble. The treble is within my tolerance; the signature is close to C16 but with less resolution. It handles violins and string quartets well, reproducing the brilliance well. I appreciate A10 complementarity with C16 and AS10 in my IEM universe. KZ AS10 (AS10) My first all-BAs, and still is one of my favourites. I commonly perceived it as a warm IEM with a quite rolled-off treble. Now, while testing several IEMs, it does not feel overly rolled-off compared to X6 for instance. There is enough treble to provide nice resolution. The bass is a bit overstated compared to other all-BAs discussed, as if featuring some traits of DDs, like spreading a bit into mids. I feel that it was really great that it became my first all-BA IEM (rather than X6, for example). I still like it quite a bit after almost a year of active use. Mids are nicely resolved, they have a bit of graininess when listening to strings due to less dampened BAs. I personally really like these graininess, it feels close to how string instruments sound live in the close vicinity with the bow engaging the strings. The highs are enough for the resolution again, definitely not overwhelming but not overly lacking. A10 has more treble, which in some violin recordings can be nicely appreciated. The low impedance makes it quite sensitive to the source, with the background hiss being quite noticeable with the smartphone (made me realize that Samsung S9 is nothing special at all for the audio, another disappointment with Samsung not to further digress…) With the decent source, AS10 shines; for the use with the smartphones, I would rather suggest C10 (see below). AS10 definitely colours the timbre a bit due to its quite prominent bass. I actually like this colouring, especially how it works for the strings together with the graininess (especially for string quartets slightly exaggerating the cello). It was my primary IEM before C16, I still enjoy it a lot and can comment that is proved to be durable surviving 6-7 months of intense listening. KZ BA10 (BA10) Definitely, an IEM that stands out – one of the most awkward housing and arguably still one of the best KZ tunings. Sometimes, I feel it is very close to AS10 (the drivers, impedance and sensitivity are all very similar, if not identical). At other times, I feel that BA10 is a bit more refined, more resonant, with a bit more extended treble. I got BA10 much later than AS10, when I finally could not resist the price of ~$55 and the opportunity to compare. After trying to work out ZS10, I could find the tips for the right fit and seal to wear BA10 somewhat comfortably for ~half an hour. But then those sharp edges (not only on the corners but inside) is the last drop – hurt my feelings deep from inside of my ears… It is really pity because the shells are beautiful and light, the tuning is quite nice. It can be said that it supersedes AS10 and many may prefer the tuning of BA10 to A10. BA10 has the best response to the 20 Ohm impedance adapter, similar to AS10, but more gracious and refined in becoming a bit more analytical. Well, given its current price, it may be a very good choice for those with the large tough ears. CCA C16 (C16) No, it is not just the number games with BAs for KZ/CCA - the resolution is really nice! All of those BAs do their job and a good one! In my “limited budget” IEM universe, I have not heard anything close. C16 sound is also quite balanced for me. Bass is there, not overwhelming as for the most all-BA IEMs. Treble is fairly extended, more than in AS10, less than in A10. Mids are just perfect to my senses; with some recordings the resolution is overwhelming both positively and negatively. (I try to use 1MT for “less than perfect” recordings, it works amazingly well for me for that purpose) Surely, C16 costs almost twice more than most IEMs discussed above. At the same time, I did not have any expectations or assumptions based on its cost or BA count that it should sound better. With the law of diminished returns, it will always remain a dilemma: to choose C16 or A10 with a lot of similarities and capabilities at about half the cost of C16. My only grudge with C16 is those plastic nozzles, which barely hold the tips (but do hold compared to X6!) and the nozzle mesh that is quite dense and hard to clean from the dirt. The aluminum nozzles of A10 (and several other IEMs) are much better to my taste and user experience. AS10 design with the mesh inside feels more practical to me (I used AS10 more than half a year quite actively without any problems). Overall, C16 is really nice, with amazing resolution and fairly balanced signature. C16 is the best IEM (in my limited collection) to my ears for the music I listen to. KZ AS06 (AS06) The least expensive all-BA IEM, also with the lowest BA count in this comparison. The shell design is very similar to AS10, only with the metal foil instead of the circuitry under the plastic of the top plate. With the 3 BAs (one for bass, one for mids and one for treble), and the BA for mids not being a broad-frequency one, the end result is the V-shape. The bass feels nice and present, the treble is there, quite reasonable, while the mids are recessed. The resulting signature is a bit dry and analytical to my ears, but not unpleasant or “off”. It is more of my listening preference to have well-resolved mids. One genre, where I feel AS06 really shines, is the solo cello music (e.g. of J. S. Bach). There the bass BA takes the show with its mighty presence, and the other two BAs competently provide the overtones for the vibrant representation. By contrast, the solo violin music sounds a bit constrained due to the recessed mids and not fully engaging the main strength of AS06, its bass BA. Overall, a very competent niche IEM for my tastes, with a strong pronounced bass. CCA C10 (C10) The first IEM with a dynamic driver in this comparison after all-BA IEMS, and it felt so different right away. The bass is so much more–in quantity and so lingering in its presence due to what feels as a much longer decay of the DD. The mid-bass feels overwhelmed as well. The mids, resolution and treble are really nice to my ears. The treble is gently rolled off, but the resolution is there. The fit is one of the best for me, since the shells are smaller compared to C16 and AS10. CA10 build and appearance also gets the highest mark from me (irrespective of the price and especially given its price). My strong personal preference is for the BA bass, but thinking more generally, C10 is the IEM that I would mostly recommend at the moment for under $30, (I have not heard ZS10 Pro yet, but decided to order it after revisiting C10 and CA4 in this comparison). KZ ZS10 (ZS10) My first KZ IEM. While its overall signature with a bit overwhelming bass was not exactly to my liking, I could appreciate its resolution and coherence, and it started my KZ/CCA journey. The housing is quite large, so it took me some time to learn how to find the right fit with the tips, which gave me some valuable experience. Revisiting ZS10 for this comparison, the sound is not that far to C10, with C10 feeling a bit more refined with more contained bass and definitely nicer fitting shells. The bass DD in ZS10 feels a bit overwhelming (definitely too much for my taste). The treble is a bit rolled-off, but then violin music still sounds quite nicely. The cellos though sound much better to my taste with the bass BAs. Overall, unless to suit to some specific tastes, ZS 10 feels more of a “history” to me, given the capabilities of C10 and ZS10 Pro that are priced similarly. 1 More Triple (1MT) 1MT was my first hybrid IEM that made me to experience a gentle side of BAs first. Sure, I can agree that its signature may be called underwhelming, but I started to appreciate how amazingly gentle and non-intrusive 1MT tuning is. BAs are fully functional to provide an unmistakable sense of the resolution and the fast response. I feel that I was lucky that it was my first hybrid IEM. Otherwise I could be easily scared by BAs. Nowadays, I commonly use it to listen to YouTube, compressed mp3 files and some less than ideal older recordings. It is much faster to insert and remove not being “over the ear” design. The non-removable cable is very much “old days” but not overly microphonic and is quite robust to all the handling and mishandling that it was subjected to. Also I did not know first that BAs are fragile and was knocking the robust aluminum housings of 1MT all around (before I became aware and scared of BA fragility), no consequences noticed luckily. 1 More Quad (1MQ) I’ve got 1MQ for under $150, just because I was (and still is) very much fond of 1MT. No, it is not worth twice as much compared to 1MT, in my opinion. The design is really nice though, though at this price range the non-removable cable may feel as a near-fatal limitation that blatantly deprives of the essential HiFI experience: “how this and that cable improve the sound” The tuning is quite unorthodox for the hybrids with the DD being given more prominence in the mids, while BAs do not extend overly into treble as well. As a result, with 3BAs covering a more narrow frequency range, the resolution is nice and the sound is very smooth for BAs. Overall, its V-shape sound is supposed to be more fun compared to 1MT. The overall sound signature should be a good match for those who prefer DDs. I am quite OK with it, but do prefer all-BA IEMs. Fiio F9 Pro (F9P) It was quite surprising to realize in this comparison that this ~2-year-old IEM still sold for ~$130-140 does not have any “wows” to offer for me anymore. Knowles BAs are definitely smoother, yet the tuning does not feel smooth with quite extrovertly spiky treble (or high mids). While the shape of the shell is really nice with the design deserving all the high praise, and the compact size is very comfortable, the angle and the size of the nozzles are a bit off for me, so perhaps I cannot fully enjoy the fit. I used F9P to listen to treble-rich violin music, but now C16 and A10 took over for me. I still think it may be competitive with A10 (and better for some), but the price (that likely implies some premium for the brand) is not quite commensurate. C16 offers much more than F9P in sound, in my opinion. Fiio FH1 (FH1) FH1 has a really nice plastic shell, reminiscent of an eye, quite catchy. My purchasing decision was significantly influenced by its appearance. With the similar shell shape as F9P, the fit is a bit better for me likely due to the nozzle. I used to like FH1 warmer signature, when I first got it, but then at some point, I started to feel the crossover listening to cello music (and the best crossover is the one you do not notice at all). Now, based on its sound, I would subjectively rate FH1 in between ZSN and CA4 (an analogue of ZSN Pro). This rating perhaps can be argued with, but then I could not imagine who would possibly prefer it over C10 based on the sound. Then Z10 Pro may be even more convincing at about half the price. Macaw GT600s Pro (GT600P) Perhaps, the most rarely mentioned IEM in this comparison, I have not seen many reviews for the “pro” especially. The nicely tempered stainless steel and glass plate of the shell are very stylish and one of the best designs that I have experienced. The fit is quite nice for me, though a bit small (the shell is nicely compact). The shell is also one of the heaviest (steel and glass are heavy) but it does not create much discomfort, just its presence is felt a little bit. The sound filters are a nice feature, though for me the treble-rich one was by far the most suitable choice. The cable, while looking nice, was a real disgrace - starting to become both green and black/brown in few days. Also the connectors did not feel convincingly sturdy. Since I did not have a good MMCX cable at the time, I largely stopped using it. Now, comparing GT600P with other IEMs, I can see that it can be rated as the best DD-BA hybrid that I have. The bass is punchy and not sluggish, the highs are really there. Despite fitting into the V-shape profile, the resolution and mids are quite competent, and the sound is well competitive with CA4, while different filters are a nice positive feature of GT600P. Its cost was ~$70 for me, which may be the main reason that it is not heard of much anymore (that and the awful cable). Final E3000 (E3000) The only single dynamic driver and non-“Chi-Fi” IEM in this review. I thought to include E3000 because of its price being in a comparable range and for a more contrasting comparison. The size of the shell (and the driver) is very small. I actually bought E3000 to play music at bed and while sleeping – the idea did not work in general, but E3000 actually suits very well for this purpose. The shell is so small that it fits completely inside my ear quite comfortably. The tips are really nice. The cable is non-detachable and the thinnest cable that I ever experienced (not that the thinnest cables feel better). The bass is quite present, amazing given the size. The mids are quite nice, but the treble, the sparkle and resolution are missing for me. I bought some $12 ($15 Can) iHaper (graphene driver) of a similar size/design, and the highs were much better to my ears, not the lows though. Overall, to my ears and sound preference, E3000 does not offer anything special, especially for its price. Finally, a brief overview of several budget two-driver DD-BA hybrids, some of which, I feel, represent the greatest value (by the virtue of the law of diminished returns) and happily for me the IEMs that are reasonably sufficient for my enjoyment of music. KZ ZSN (ZSN) It served as a reference point for me to define the boundary, where the sound, fit and build were satisfactory for the great price. The design, build and fit are outstanding for ~$15, in my opinion. The V-shaped sound is quite fun and does a very reasonable job for all music that I listen to. ZSN can serve as an IEM, which I can “listen to for the rest of my life”. (Important to note, this statement holds when the DAP is used. The difference with using Samsung S9 is very noticeable and greatly exacerbates the fact that S9 did not receive good audio implementation, being not the very top Samsung model (S9 will be my last Samsung)). No difference between the cyan and purple ones using the same balanced NiceHCKcable (that I can perceive): the same cheerful V-shape with quite competent dynamic bass and sparkling highs of the BA. Only few months ago, before CA4 and ZSN Pro were born, ZSN was the top IEM at ~$15 for me. ZSN is still a competent IEM, but the improvement of the tight bass in CA4 (and similar ZSN Pro) is quite prominent and a very positive change in line with my preferences toward the BA sound. CCA CA4 (CA4) Different from C04 (which is a clone/sibling of KZ ZSA), CA4 is the current best “budget” (at ~$15 range) IEM of the latest generation for me, a noticeable improvement relative to ZSN (and ZSN again served as a reference for the best budget IEM for me and, importantly, the minimal acceptable sound to enjoy my music). CA04 feature really comfortable fit, similar to C10 and perhaps the best for me at the moment. Tight bass, least “dynamic” DD to my ears. The V-shape is there, at the same time it feels more refined compared to ZSN. The treble is really good for a single-BA hybrid. The mids are decent, but not to compete directly with multi-BAs. After re-visiting CA4 (and C10), I finally decided to get ZS10 Pro to experience the most acclaimed hybrid from KZ at the moment in a similar very comfortable shell. Overall, CA4 takes the crown for me in the price category of ~$15 (I strongly prefer at least one BA to a single-DD design). CCA C04 (C04) & KZ ZSA (ZSA) I thought to include C04, since it seems to be less known and less reviewed and also can be confused with the newer CA4. The first CCA IEM and my first CCA. A rebuilt/reworked KZ ZSA, as far as I can tell from the description and the sound. The all-plastic (blue-green in my case) shell is unique to CCA (almost round top plate). I like its appearance. While its close sibling, ZSA, also has a very nice aluminum shell, it is quite a bit small to fit my ears nicely (it was great though to discover a lower boundary of the IEM size after trying to fit ZS10 and BA10). C04 sound is a bit more refined V-shape compared to ZSA to my ears, but more V-shape than ZSN. Compared to CA04, the sound is a bit rougher: not as fast bass and less capable BA. Still C04 can do a competent job in reproducing solo violin music. I could not help listening with C04 for half an hour –while not perfect, very decent and acceptable to me. Unfortunately, with its price close to CA4 and ZSN Pro, it may be a bit of an extinct breed now due to the fast and relentless IEM evolution – nice for some IEM collection, but not a prime competitor. The fact that C04 shares a (yet another) unique variation of the two-pin connector with ZSA does not help as well. DT6 The last IEM in this comparison is a unique hybrid of a piezo, a BA and a DD drivers. The keyword to characterize DT6 that immediately comes to mind is “fun” (great fun given its price of ~$20). The bass is rich and not overly lingering and intruding into the mid-bass range. The mids are quite reasonable, and the treble is sizzling. I am still not entirely sure that the piezo driver plays an overly prominent role (typically the impedance of a piezo element is quite high, so high voltages are usually required to drive it, while the impedance of DT6 is surprisingly “normal”). Despite my scepticism, owning an IEM with a piezo driver just feels nice, perhaps similar to using ultra-low resistance cables . I really enjoy listening to DT6 from time to time: the sound stage feels mighty spacious, and hearing pianos (especially when piano duo is playing) being thoroughly dissected in space is quite entertaining. Those, who may insist on spatial and timbre realism, will need to look elsewhere though. I typically wear DT6 “cable-down” though “over-the-ear” fit works quite OK as well, when flipping left and right (as I learned from the fellows Head-Fi-ers here) Overall, despite my perhaps overly expressed criticism, I would highly recommend DT6 as a unique and fun IEM, especially given its capabilities-to-price ratio. Concluding remarks IEM-specific: X6 and A10 were quite interesting to experience, while neither of them happened to become revelational for me, more of a niche fit. A10 is taking over F9P in a treble-rich niche. X6 is nice to experience music with the nicely resolved mids, as long as the bass is not overly present and the rich treble is avoided. C16 and AS10 still remain my favourite IEMs, first for its amazing resolution, the second is for its nice bass and gentleness with still enough resolution. BA10 could triumph over AS10, if not for its size and especially those sharp edges. General: Firstly, I have way too many IEMs… Secondly, it was surely a lot of fun to experience and re-experience all of them (while still remaining relatively reasonable for the budget due to adhering to my self-imposed limits). I still plan to experience at least few more CCAs (C20, C18?) that can serve as upgrades rather than side-grades. Lastly, I hope that this comparison can be of use to Head-Fi members, to whom I feel indebted for generously sharing the wealth of Hi-Fi knowledge.