Mids sound a lot more lush/detailed in a sense (less "distant" sounding) than the CLAS -dB + ALO Rx Mk3-B+ combo (in balanced back-end mode) using the IE800, but that is just my intiial impressions/comparison so far. I was actually quite surprised at how "small" the Theorem 720 actually is (it seems less "fat" in terms of horizontal width than the Fostex HP-P1 or CLAS/ALO, although a bit longer than both the Fostex and original CLAS), it seems it might be slightly more "pocketable" (or at least easier to handle in portable-use situations) than the Fostex HP-P1 even.
The background "hiss" with the IE800 still exists as on the CLAS -dB + ALO Rx Mk3-B+ combo, but it's completely tolerable and I don't mind it. I'd say that the levels of hiss on both the Rx Mk3-B+ and Theorem 720 w/ the IE800 are just about the same, but disappears/is easy to ignore once you have music playing (even during "quiet" passages.)
Edited by refault - 1/17/14 at 2:18am