It occurs to me that there aren't a lot of impressions about the A12t/U12t, as an owner of the A12t I feel obliged to gift you with my personal opinion. I paid full price for these A12ts and 64 Audio is not forcing me against my will to write this... For the entirety of this review I was using DX200 AMP3 as my source Fit/Build: I bought the custom version, so the fit is fantastic. They did an outstanding job making these, the quality is superb...they cost $2000 so they damn well better be superb. The Koa wood I ordered looks outstanding, but I would have liked to have more options for custom design. The only qualm I have with the build is a small one. The 2-pin connector area housing is a bit small, because of this I cannot fit some of my cables 2-pins fully into the IEM. The cables are able to go in enough to work, but I worry they will come out. **I have tried the universals and I found them to have a good fit, but I cannot comment on specifics.** Sound: prelude: The A12t are undoubtedly better than their older brother the U12/A12, but share a similar signature. The Tia helps maintain an authoritative bass while clearing up some of the mud from the last iteration. They work well with most genres, but if you like Classical, or Metal I'd suggest getting something like the Andromeda, or upgrade and go for the U18t/A18t. The A12ts are good, they are very good, these headphones play music really really really well, but they feel like they are missing a personality. They are the straight-A student who doesn't have any hobbies, the person who is good at everything, but doesn't have any foibles or quirks. The highs are clear, the sound-stage is vast, the background is black, the mids are ever present, they are somehow both warm and clear, and that bass...wow that bass....If any headphone was capable of producing the fabled 'brown note' I imagine it would be a headphone from 64 Audio. Bass: I had heard the old U12s without the Tia and I will say that they have been noticeably re-worked. I'll start by talking about what many are going to consider the best feature, the bass. The bass is large, larger than the Vegas, but since these are BA IEMs it doesn't bleed into the the mids quite as much. It is also quicker and able to keep pace with faster music, but also has this frightening, primal rumble....like drums in the deep. My issue with the Vegas, and the previous U12s, was that I felt that they were all bass, but I don't feel this way about the A12ts. The addition of the Tia has really put balance into the other frequency ranges of the A12ts. Highs: The highs aren't excessive, I've been listening to a lot of my Galaxy V2s, which at times are a very sharp headphone. Because of this I find myself cringing in anticipation of a piercing high-note that never comes from the A12t. While the highs don't hurt, they still sparkle, it's a pretty fantastic balancing act that 64 Audio has accomplished with their Tia technology. Mids: The mids are good, nothing to write home about, but considering how deep the bass is and how clear the highs are that is impressive. To me they still feel a bit recessed, vocals and guitar have a nice timbre to them, but still sound a bit muffled. With the Vegas I didn't really feel like I could listen to Rock, but I do feel like I can with the A12ts, especially with the m15 Apex module, which reduces the bass and opens the sound-stage up a noticeable amount. Music Genres and Your A12t: --I've picked a handful of genres and used artists that most people will be familiar with-- Folk-ish: (Artist: Sturgill Simpson) As I said in the brief 'mids' section I find this to be a difficult genre for the A12ts, because I find that the mids are not the highlight of this particular IEM. I'd rather be listening to my Andromedas, but these still sound competent and are laid-back (aka a bit warm/muddy), but it is still enjoyable. Rock: (Artist: Nirvana) Sounded pretty damn good. The BA were able to keep pace with faster riffs, same muddishness, but I really enjoyed going through Nirvana's catalogue again. Metal: (Artist: Mastodon) Didn't have the clear sound that other BAs have, but it didn't feel too slow for the genre like some DD IEMs sound with metal. If I were a metal-head I'd want something a bit clearer/faster. I don't think warm sounds match very well with faster metal. Electronic: (Artist: Deadmau5, Sylvan Esso) Outstanding. This is the sweetspot for these, I think. Often times there is female vocals in Electronic music and the A12ts did the female vocals very well, then the bass drops...its a fun experience. The m20 is even better, it makes the sound-stage smaller and really pushes air into your brain. Rap: (Artist: Notorious B.I.G) Great. Great bass and highs make both the beats and the lyrics standout in a good way...again listen with the m20 module. Classical: (Artist: Vivaldi) I found it kind of hard to separate all the instruments. The sound-stage is very wide and opened with the A12ts, but to distinguish between all the instruments I found myself continuously turning the headphones up. Punk: (Artist: Idles -- "Brutalism" is a great album, if you are a fan of the genre, or looking to get in, download it.) This actually wasn't too bad. I found the A12ts to lend a nice warmth to a somtimes harsh sounding genre. Female Vocals: (Artist: Sheryl Crow) Female vocals sound soft, but not saccharine. There is a nice airy-ness coming from the Tia that gives female vocals an interesting timbre. Cables: Stock: Not bad! I actually used the stock cable from my Iphone X and the sound was pretty good...I don't like the stock ear-guides though Leonidas: The best match, in my opinion this cable makes everything sound better. Rhapsodio SG 2.98: Nice sound, clear, warm, a really good pairing Rhapsodio Silver: Pushed the highs to almost too almost too bright of a place, but cleaned up the signature a lil Triton8 Hybrid: Helps clarity while maintaining the bass TL;DR/Conclusion: In closing, the A12t does a lot of things well, but they are missing the X Factor. It reminds me of the Sennheiser HD650s, they sound amazing, but I never wore them...why? Because they aren't bad-ass, they don't get into trouble, because they don't take a ton of chances. Would I buy the the A12t again? Absolutely. Would I recommend them? Yes. If you are looking at these you need to like music that has bass. If you are getting them to listen to Metal, or Classical, I'd look elsewhere. If you are getting them to listen to Rap, Electronic, and more modern indie music...then get them and do yourself a favor, get them custom.