The comparison was done using U18s with a stock cable, SpinFit stock eartips, M20 (unless noted otherwise), and LPGT source; volume matched in every comparison.
U18s vs A18s
Custom 18s just didn’t work out for my ears. As I have mentioned already, my left ear has a sharp first bend and as a result custom nozzle is usually trimmed down to look almost like universal, and right earpiece nozzle has to be short to match the left one. With some iems it works, but not with all of them. Doesn’t mean U18s and A18s were tuned differently. It just means that custom shell with a very short nozzle skews the intended sound tuning where to my ears A18s treble was not as extended and upper bass and lower mids got thicker, giving the sound more body and some bloat, taking away from clarity and making vocals sound off. But when I got universal demo of A18s and later received the final U18s, their sound was nearly identical which makes me believe that U18s and A18s with an adequate nozzle will sound the same as well. And U18s will give you another level of sound tuning through tip rolling.
U18s vs U12t
The first big difference that stands out here is the treble with 18s being smoother and more organic while 12t being crisp and sparkly, more air and better extension. In theory they should have the same tia driver, but it is tuned completely different. Next, as you shift your focus to mids, you hear brighter vocals with neutral lower mids body, making vocals more revealing and thinner, while 18s has a lot more body with vocals sounding thicker and warmer. Using M20 module, 12t actually has a surprisingly deep sub-bass rumble and good mid-bass impact, though scaled down in quantity and with bass having shorter decay, thus lower mids being more neutral.
U18s vs U18t
This is a very interesting comparison because I’m sure people will expect a lot of similarities, while in reality there are more differences. Regardless of the module you use, tia driven treble is not the same between 18s and 18t, with 18t being brighter and crisper while 18s being smoother and more organic. Then, at the other end of the spectrum, you have a different bass tuning. The bass of 18t with M20 module sounds close to 18s with MX module, extended but neutral in quantity. Yes, you have to attenuate 18s bass by more than 10dBs to match it with 18t and M20. Also, I have a feeling that 64 Audio didn’t change the mids tuning going from 18t to 18s, but due to sound changes related to bass and treble, the perception of 18t mids is more revealing, more forward, and with a better layering and separation of the sounds, while 18s mids sound more organic.
U18s vs Nio
Finally, a comparison where we have a closer match in bass. Until Nio, I was enjoying the sparkle of tia treble in other 64 Audio iems, but after spending more time with Nio, my ears adjusted to a smoother tonality of its treble tuning. I wouldn’t say the treble here sounds identical, and I find 18s to have a little better extension, more refinement, and better controlled crunch while Nio treble is a bit raw and forward in presentation. Bass comparison here is interesting as well. We are talking about DD vs BA, and Nio with M20 is a bass cannon with a noticeable sub-bass lift and very strong mid-bass slam. Dropping Nio from M20 to M15, I still feel the bass quantity is higher than 18s with M20, and for my personal taste I prefer Nio with atom N10 (10dB module). In comparison, 18s bass is less aggressive, more polished, less raw. If you are closeted basshead, 18s might not fully satisfy your craving, like Nio with M20. When it comes to mids, 18s is more refined, better layered, and also a little more laidback.
U18s vs Fourte/Noir
I always had a love/hate relationship with Fourte/Noir. When it was released alongside the U18t, I preferred 18t tuning, but later made peace with it after I switched from silicone to foam eartips. To my ears with silicone eartips the Fourte/Noir treble is piercing, but it becomes smoother and less peaky with foamies, though I still find it bright, even brighter than U18t/12t. Fourte/Noir bass is velvety smooth and textured, not as aggressive in comparison to 18s stronger mid-bass impact (w/M20), but the sub-bass extension is quite similar with its deep analog quality. With mids/vocals in A/B comparison using stock cable, Fourte/Noir vocals sound hollower and more withdrawn in comparison to 18s. I do prefer Noir over Fourte because of its fuller lower mids body which gives vocals more natural tonality, but Fourte/Noir both have 1kHz peak which to my ears makes the sound a bit hollow and nasal, the reason why I prefer 18s/t in this comparison. All just a matter of a personal preference.
64 Audio Family picture.
U18s vs Oriolus Traillii
To level the field in this comparison, I was using U18s with PWA 1960 4 wire cable. The soundstage depth/height are quite similar, but the width is different with Traillii being wider, creating more holographic effect while U18s being more focused and a little more intimate in soundstage presentation. When it comes to bass, both have a very similar mid-bass punch, perhaps with U18s being a little stronger while Traillii having a deeper and more textured sub-bass rumble. U18s sub-bass extension is no slouch either, but Traillii just has more quantity and more weight in sub-bass. Mids are actually quite similar in this comparison, with fuller body lower mids and natural detailed tonality of upper mids/vocals, though technically Traillii has better layering and separation of sounds in mids. Both have a natural well-defined treble without any harsh peaks, but Traillii has more sparkle and airiness in comparison to smoother treble extension in U18s.
U18s vs VE Erlkonig
There is a slight difference in soundstage expansion and imaging between these two where I find Erl to have a little wider soundstage while both have the same depth/height, but mids positioned a lot closer in Erl while being extended more out of your head in U18s. With M20 module, U18s bass also hits harder, mid-bass quantity is more elevated, while sub-bass extension is similar in quality, just a touch more elevated and textured in Erl relative to U18s. Both have a very similar natural detailed upper mids, but Erl lower mids are fuller and warmer in comparison to U18s being relatively slimmer. U18s lower mids are not lacking any body, but in a relative comparison Erl lower mids are fuller, giving its sound a thicker vocals. With treble, Elk has more sparkle and airiness. Both have a well-controlled natural treble but the upper treble sparkle and air is more noticeable in Erl.
Source pair up.
In each source pair up I was using a stock Premium cable with balanced termination (I have another Premium cable with 2.5mm termination, used with 4.4mm adapter if necessary) to keep everything consistent. U18s is easy to drive considering its 106dB sensitivity which might need only a few extra volume clicks. Also, due to its LID tech, U18s low 8ohm impedance didn’t seem to cause any issues with different output impedance sources, even 10ohm original R6. Also, I didn’t hear any hissing. For your reference, here are my brief pair up notes. And by brief, I just focus on any changes related to signature and general tonality, without going into too many details of technical performance difference.
Lotoo LPGT (baseline) – balanced sound sig, deep enhanced bass impact, natural detailed mids, smooth detailed treble.
Hiby R6 (10ohm output impedance, original model) – a similar signature, with a little stronger bass impact.
iBasso DX160 – a similar signature, just a little more revealing mids.
A&K SP2000 SS – a similar signature with a little bit more sub-bass rumble and some extra treble sparkle.
L&P P6 Pro – a similar signature with more sub-bass rumble, smoother yet still detailed vocals, and similar treble.
iBasso DX300 – a similar signature with a touch more sub-bass rumble, the same natural tonality mids and treble with a little more sparkle and air.
Hiby R8 – a similar signature with an overall slight enhancement of sub-bass rumble, more revealing mids/vocals, and more sparkle in treble.
Galaxy S9 (smartphone) – a similar signature, but leaning a little more toward U-shaped since mids/vocals are slightly recessed, while bass has more impact and treble has a little more sparkle.
Maybe there are some slight variations going from dap to dap, but overall U18s signature remained the same, thanks to LID tech which does work. In comparison, it was a different story with U18t where I heard more variation in sound.
I know, U18s is just one of 3 new 64 Audio releases announced early this year. And I’m well aware of the reaction U18s received on Head-fi when details leaked out ahead of the official release. People wanted something all new and totally different, and I have a feeling it is still to come! From the image of 3 new releases shared during their new product announcement, we already know about U18s, and many are speculating that one in the middle could be a wireless model (just a speculation). There was also a 3rd model will an open back grill, so I’m keeping my fingers crossed for the next big flagship announcement. But it doesn’t mean that U18s release has to be discounted.
A/U18s finally got a well-deserved proper introduction, catering to musicians who prefer mostly CIEMs and audiophiles who go for both CIEM and UEIM versions. Also, I personally think that U18s wears two hats under that “s” suffix. With MX module you can look at it as a studio IEM with more neutral bass and clear focus on mids and treble that should work great for studio mixing and monitoring. But switching to M20 module turns it up to “eleven” with a sound signature for stage musicians and audiophiles who crave natural detailed analog tonality and powerful bass slam without overwhelming ear fatigue. Now, add to that a cool new faceplate design with 64 Audio logo branded apex modules and the package is complete!