I have the non-cryo 20 amp version. The ACME IMS has a very quick and transparent sounding mid-bass, and presents a wealth of upfront detail. Not etched sounding, but you get the sense you're hearing everything in a very transparent space. I was quite happy with the ACMEs until I heard the FIMs in my system. The comparison made the ACME sound like its tonal balance was tilted up in the upper mids, and by comparison a very fine dry grainy quality became noticeable from the mids up. The FIM is slightly darker, but more natural and smoother sounding. Initial impression with the FIM is that there isn’t as much detail, although its all there, some details just have a more distant perspective. Just my take.