Sound Analysis.

When analyzing U18 sound, you have to look at a separate pair up with M20 and M15 modules, like a switch between two distinct sound signatures. Prior to starting my critical listening, I did put U18 through 100hrs of standalone burn in, but that was more for a benefit of the cable as well as making sure that all the solder joints, internal wiring, and crossover components have reached their prime condition. Either if you believe or don’t in a burn-in, for me it’s almost like an OCD routine I go with every piece of audio gear.

The first thing I noticed with U18, regardless of the module, is a very open and expanded sound like you would hear from a full size open back headphones. Also, while listening to U18 for extended period of time, I’ve never experienced an ear fatigue or a pressure associated with some other sealed iems, and that experience was very similar to my previous testing of U6 and U12 with various APEX and ADEL modules. Furthermore, I was very impressed with the coherency of driver tuning where all 18 BAs work together in a perfect unison.

When it comes to the actual sound with M20 module, you get a full body balanced signature with a natural transparent tonality. Regardless of the type of instruments, real or synthesized, the timbre accuracy was convincing to my ears, and the same goes for vocals, either male or female, sounding natural and realistic. The sound has excellent retrieval of details, not on an analytical level but in its own natural way with a high level of clarity surrounded by smoother edges. U18 is quite forgiving when it comes to a poorly recorded music, and also works great paired up with various high res, mid-fi, and even some low-res sources.

Starting with a low end, you get a deep textured rumble which you can actually feel since it’s not just an extension but actually has a tasteful boost in quantity. Mid-bass has a speed typical of BA drivers, with a faster attack, but the decay is a little longer, giving the bass a bit of a dynamic driver characteristic with some additional body. Overall, bass is very well controlled, articulate, layered, well rounded, and with no spillage into lower mids. Lower mids are neutral, maybe a little toward the leaner side, and yet they surprisingly add some body to the sound. Upper mids are very clear and detailed while still retaining their natural smoothness. Interestingly enough, I don’t hear as much of air between the layers of the sound when it comes to M20 module, but the perception of the sound is still layered, transparent, and very resolving. Treble is crisp, very well defined, with a nice extension, and well controlled airiness.

When you replace M20 with M15, it feels like a switch to a different signature with a more revealing crisp airy sound that has a slightly more mid-forward characteristics, edging a bit more toward analytical level. This sound is a little more critical, not as forgiving with a poorly recorded music, especially if there are some spikes around 5k-6k area in the recorded material.

With M15, bass becomes more neutral in quantity, with a less pronounced sub-bass rumble which you can still hear very well, but the quantity is reduced. The same with a mid-bass being not as intense, definitely with a little less impact. The overall bass is still very articulate, layered, well controlled. Going up to lower mids, they sound a little leaner in comparison to M20, though the sound never feels like being v-shaped. With a lower quantity of the low end, the upper mids perception becomes a little more forward, brighter, leaning more toward the analytical side and will a little more airiness between the layers of the sound. Treble is still crisp and clear, but has a little more crunch and more airiness which can push some poorly recorded tracks toward a little harsher tonality. The sound becomes more revealing, less forgiving.

Regardless of M15 or M20 module, as I already mentioned, the sound is very open and has a natural expansion of the soundstage in all 3 dimensions. I do hear a very wide staging, but it’s still realistic, not exaggerated. The depth of the sound is not too far out of your head and not too close in (not too intimate), feels like you are 3-4 rows in front of the stage. The separation and layering of the sound is excellent, regardless of the modules. As a matter of fact, even with M20 where you have more bass impact and slightly less airiness between the layers – layering and separation of instruments and vocals is still great, there is never a feeling of a sound being congested. The same with imaging having a very convincing positioning of instruments and vocals, a rather accurate positioning where you can easily pin-point every sound.

APEX modules.

Depending on your tonal preference, U18 has enough tuning flexibility between M20 and M15 modules to adjust the sound to your liking. In a summary:

M20 (aluminum finish) – more bass impact, more body in lower mids and overall sound, more organic natural presentation of upper mids and vocals, and a little smoother treble while still retaining the same level of airiness and resolution.

M15 (gunmetal finish) – more neutral bass, less sub-bass rumble, more neutral leaner lower mids, brighter, a bit colder, and more revealing upper mids, and crisper treble.

At the end of the day these modules are just another set of tools to fine tune the sound of 64audio IEMs. If I want more bass and smoother sound in U18, I switch to M20, if I want more neutral bass and more revealing upper frequencies I switch to M15. It will also depend on the pair up and the signature of the source. I’m not sure if it would be right to say that one module is better than the other, they just do a different job where everything is up to a personal preference.

Pair up.

In my pair up test with different sources, I decided to be consistent and use U18 with M20 module along with an included 3.5mm SE stock cable. While U18 has an average 115dB sensitivity, I wasn’t sure what to expect due to its 9 ohm impedance and how it will affect the hissing with different sources.

Lotoo PAW Gold – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass, well controlled articulate bass, neutral lower mids (a touch on a leaner side), very detailed, revealing, layered, transparent upper mids, crisp well defined airy treble. No hissing.

FiiO X5iii – spacious soundstage, textured sub-bass rumble with a little less quantity, punchy mid-bass with a little slower speed, bass is articulate but a little slower, a little more body in lower mids, clear, detailed upper mids, crisp well defined airy treble. Very slight hissing.

theBit Opus#2 – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass, well controlled articulate bass, neutral lower mids, detailed, revealing, layered, transparent upper mids, crisp well defined airy treble. No hissing.

theBit Opus#3 – very spacious soundstage, deep textured sub-bass rumble, punchy mid-bass with a moderate speed, well controlled articulate bass, neutral lower mids, detailed, revealing, smoother upper mids, crisp well defined airy treble. No hissing.

Cayin i5 – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass with a healthy doze of impact, well controlled articulate bass, neutral lower mids, detailed, revealing, smoother upper mids, crisp well defined airy treble. No hissing.

iBasso DX200 w/AMP2 – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass with a nice impact, well controlled articulate layered bass, neutral lower mids (a touch on a leaner side), very detailed, revealing, layered, transparent upper mids, crisp well defined airy treble. No hissing.

FiiO X7 w/AM3 – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass with a nice impact, well controlled articulate layered bass, neutral lower mids (a touch on a leaner side), very detailed, revealing, layered transparent upper mids, crisp well defined airy treble. No hissing.

Cowon Plenue 2 – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass, well controlled articulate layered bass, neutral lower mids (a touch on a leaner side), very detailed, revealing layered transparent upper mids, crisp well defined airy treble (a little extra sparkle). No hissing.

A&K AK120ii – spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass, well controlled articulate bass, neutral lower mids, very detailed, transparent upper mids (a little brighter upfront presentation), crisp airy well defined treble. No hissing.

iFi Micro iDSD – very spacious soundstage, deep textured sub-bass rumble, punchy fast mid-bass, well controlled articulate layered bass, neutral lower mids, detailed, revealing layered, transparent upper mids, crisp well defined airy treble. No hissing.

Samsung Note 4 – spacious soundstage, nicely textured sub-bass rumble, punchy mid-bass, well controlled articulate bass, neutral lower mids (a bit on a leaner side), detailed, revealing upper mids, crisp well defined treble. No hissing. Of course, the sound with my aging smartphone is not as resolving as with some of the DAPs, but it was still a great pair up. 

Comparison.

Using both LPG and Plenue 2 as my sources, I kept U18 with a stock SPC cable and M20 module, and volume matched every pair by ear. Also, I noted which cable was used with other C/IEMs in comparison to U18, and if necessary used EA 2.5mm-to-3.5mm adapter.

U18 vs ES80 (Ref8) – soundstage: 18 has more width while 80 has more depth; 18 has deeper sub-bass with more rumble and faster mid-bass with more impact. 80 bass is more neutral, and sub-bass extension is not as deep. 18 lower mids are a little leaner while 80 is a little more neutral with more body. 18 upper mids are more revealing, more resolving, while 80 is smoother and a little warmer. 18 treble has more sparkle and more airiness. Overall, 80 is more neutral while 18 is more balanced and also more resolving, more layered, and more transparent in comparison.

U18 vs ES60 (TWag v3) – soundstage: the depth is very similar, but 18 has more width; 18 has a deeper and more textured sub-bass with more mid-bass impact. 60 sub-bass is lower in quantity, and mid-bass is not as articulate, overall ES60 bass is not as tight. 18 lower mids are a little leaner while 60 is more neutral with more body. Both have a revealing upper mids, but 18 is more layered and with better retrieval of details, while 60 is a little smoother. Both have a sparkly airy treble, but 18 has a little more airiness and better extension.

U18 vs W80 (Ref8) – soundstage: 18 has more width and depth; both have a very good sub-bass extension, but 18 has more rumble and more texture, both also have a nice mid-bass impact, but 18 is tighter and more articulate. 80 lower mids are more neutral and with more body while 18 is leaner. 80 upper mids are smoother, warmer, more organic while 18 upper mids are more layered, more revealing, with better retrieval of details. Both have a good treble extension but 18 has more sparkle and airiness.

U18 vs Zeus XRA (Ares II) – soundstage: both have a similar depth but 18 has a touch more width; while XRA sub-bass has a good extension, its very neutral and sounds flat in comparison to a lot more rumble and texture in 18 sub-bass, both have a fast mid-bass with 18 having more impact; while both have a well controlled and articulate quality bass, the bass quantity (especially lack of sub-bass rumble/texture in XRA) is the biggest thing that sets them apart. Both have lean lower mids, though 18 has a touch more body, and both have a layered revealing upper mids while 18 has a touch smoother tonality while XRA has a little more air between the layers of the sound. Both have a good sparkly treble extension with lots of airiness, though XRA treble can get a little more piercing. Also, with Zeus XRA you hear a higher level of hissing with LPG/P2, while 18 was down to a minimum.

U18 vs W900 (1960 4w) – soundstage: a very similar soundstage width (here, W900 greatly benefits from 1960) while W900 has a little more depth, projecting slightly more out of your head; both have a great sub-bass extension, but I hear 18 going a touch deeper, having a little more rumble, and having more articulate texture. Both have a strong mid-bass impact, but 18 is a little faster. 18 lower mids are a little leaner while W900 is closer to neutral with a little more body; upper mids are revealing in both but W900 is smoother and not as layered, while 18 upper mids are little brighter, with better layering and separation. Both have a very similar treble in terms of sparkle, extension, and airiness. While with Zeus it was a quantity of bass, here it’s the quality of bass that makes the biggest difference where you hear a more typical DD performance when listening to W900 vs a faster, tighter, more articulate performance of BA drivers in 18.

U18 vs K10UA (stock SPC) – soundstage: similar depth while 18 staging is wider; both have a good sub-bass extension, while 18 goes a little deeper, has more textured rumble, a little higher quantity; when it comes to mid-bass, both have a fast articulate mid-bass punch, though 18 has a touch more quantity. Lower mids are lean in both iems, while upper mids have a similar revealing layered sound, though I hear 18 having a little more air between the layers. Both have a crisp airy treble, but K10 treble is a little more piercing.

U18 vs S-EM9 (Thor II+) – soundstage: while 18 has more width, EM9 has more depth; both have a similar textured sub-bass rumble, even the quantity coming closer, but mid-bass varies in here with 18 being tighter and more articulate while EM9 being slower and a little hollow in tonality, when compared. Lower mids are leaner in 18, while EM9 is more neutral with a little more body. Upper mids are more revealing and layered in 18 while EM9 is more forward, smoother and more organic in tonality, not as layered as 18. Both have a well defined crisp treble, though 18 treble has a better extension.

U18 vs Maestro (TWau) – soundstage: both have a similar depth while 18 has more width; both have a great sub-bass extension though 18 has higher quantity rumble, both have a fast mid-bass punch, but U18 bass feels tighter and a little more articulate in comparison. Maestro lower mids are more neutral with slightly more body in comparison to leaner 18 lower mids. Both have a revealing upper mids, Maestro is a little smoother while 18 is more layered with a better definition. Both have a nice crisp treble with a similar extension, except 18 treble has a better definition.

U18 vs VEGA (ALO Litz SPC) – soundstage: 18 has a touch more width while VEGA has more depth; VEGA has noticeable more sub-bass, but it’s not as textured as 18. Also, U18 mid-bass is faster, tighter, more controlled and with a better articulation; in comparison, VEGA mid-bass has more slam. 18 lower mids are leaner, while VEGA is a little north of neutral with more organic body. Upper mids are more layered and more revealing in 18 while VEGA is a little smoother and a touch warmer. Both have a crisp airy treble, though VEGA is a little more piercing.

U18 vs Xelento (stock SPC) – soundstage: similar depth but 18 has more width; both have a deep texture sub-bass rumble that goes pretty deep, but Xelento has more sub-bass quantity. Mids bass in Xelento is slower but has more impact than U18 mid-bass, but in comparison U18 mid-bass is faster, tighter, with more control. Lower mids are more neutral and with more body in Xelento, upper mids in 18 are more revealing, better layered, a little more resolving, while Xelento is also revealing but smoother in comparison. Treble is very similar with a crisp airy well defined performance.

U18 vs UERR (stock OFC) – soundstage: similar staging depth while 18 is wider; U18 sub-bass extends lower and has more rumble in comparison to a more neutral flat sub-bass in UERR. Mid-bass in 18 also has more impact and tighter in comparison to a more neutral and a little slower UERR mid-bass. The overeall bass in UERR is more neutral and slightly more laid back. 18 lower mids are leaner while UERR is smoother and with a little more body. Upper mids are clear, detailed, and smooth in UERR while 18 upper mids are more revealing, layered, transparent. Both have a crisp well defined treble but 18 has a better extension and more airiness in comparison.

U18 vs ERIB1C (stock OFC) – soundstage: a similar staging width while ERIB staging is deeper; while ERIB sub-bass does have a good extension and a little bit of rumble, it’s very neutral and flat, definitely not a fair comparison to a more textured U18 sub-bass with a lot more impact and more textured rumble. The same with mid-bass, while both share a similar speed of the bass, ERIB is rather neutral in comparison to more articulate impact of 18. Both have a very similar lean lower mids, and revealing layered upper mids, though 18 maybe a touch smoother. Treble is where I hear more difference with ERIB having more crunch and airiness.

U18 vs U12 w/M15 (Ref8) – soundstage: both have a similar depth but 18 is wider; U18 sub-bass goes a little deeper and has more controlled rumble and more quantity, mid-bass is faster, tighter, and more articulate in 18 while 12 is a little slower, and not as controlled, spilling a bit into lower mids. Lower mids in 18 are lean while 12 are a little north of neutral, with more body. Upper mids are more revealing, more detailed, more layered in 18 while 12 is smoother, warmer, more laid back. Treble has more sparkle, more airiness and better extension in 18. 

64audio family picture (U6, U12, U18). 

Conclusion.

64audio U18tzar is one of the most expensive IEMs I had a chance to review, and it’s also one of the closest to hit a sweet spot of my sound preference when paired up with M20 module. That’s why in the last few months it became my go-to IEM. Does this mean it will be everyone’s cup of tea with everybody else feeling the same about it? It’s hard to tell because we all have a different sound preference, use different sources, listen to different genres of music, and have a different ear anatomy. Look at the other flagships mentioned in a Comparison section of my review, I’m sure there are people who have these at the top of their list. Btw, some of these IEMs along with premium aftermarket cables could cost even more than a stock U18. But either way, sometimes it makes sense to invest into one TOTL flagship that hits a sweet spot, rather than buying a handful of flagships that dance around it.

At the end of the day it all comes down to a personal preference when trying to figure out your ideal IEM. I found U18 to have a very detailed, resolving, balanced sound with a soundstage of an open back headphones. When equipped with M20 module, I hear a full body natural revealing tonality with a very impressive quality/quantity bass, and when switching to M15, I hear a more neutral, brighter, and even more revealing airy sound. It felt like flipping a switch when replacing the modules, and I was able to fine-tune the sound further by cable rolling. I know many are also interested in 64audio other flagship, TIA Fourte, and maybe I will get an opportunity to review and to compare it later. But for now, I’m holding U18 in a very high regard. Also, if you get a chance to attend your local CanJam audio show (check http://www.canjamglobal.com/ for the dates) where 64audio is often one of the exhibitors – take the opportunity to hear 64audio IEMs and other manufacturers flagships to compare and to decide which one is the best for you. Reading different reviews and impressions is important to get others perspective about the product, but nothing can substitute your own personal experience when deciding to invest into TOTL flagship IEM.