It is a shame that you only got the hear the Omni powered by a Fiio A5. That amp is woefully inadequate for getting a good bass response out of the Omni. 800mw at 32ohm is simply not enough.

It wasnt just through the A5. I will test it through my Sherwood AD203B, which is a 300w Stereo amp. I assume that's enough power for you?

Great review. Sounds like you've really had some time listening to good gear and can really pick apart what you're hearing.

@Cinder No intention of stating an argument here, but if you didn't hook the Omni up to it using speaker taps, then that amp was probably inadequate as well. Not because the Omni needs hundreds of watts, but because speaker amps/receivers often have cheap, weak opamp based headphone amps. Probably sounded worse than the A5. But I don't know anything about the Sherwood unit, so I can't really speak to it with any certainty. 

@joeq70 It was not hooked up to speaker taps. It was plugged directly into a 1/4 inch out. This particular unit was quite expensive when it was on sale, so I don't believe that it will sounds any worse than the A5. In fact, after listening, I didn't really get too much of a different experience when A/B-ing between the A5 and the Sherwood. 

It is weird though how you felt the bass wasn't that powerful when the other reviewers here said its incredible. I dunno. I was considering these since I wanted audiophile bass head phones but not sure.

@smodtactical My frame of reference at that point for bass emphasis was probably different from the other reviewers. I don't know how I'd feel about these headphones now (two years later) given how my tastes have changed.

@Cinder When you were saying they aren't crushing/rumbling... which headphones were you comparing them too?