Now that I should be studying for my midterms, I thought it a fine time to post my impressions of the Total Bithead from Headroom. http://www.headphone.com/headphone-amps/amplifiers/headroom-total-bithead.php. I got this as a Christmas gift, so no comments on the price/value as I paid $0. Yay me! Anyway, the build is quite good, with a large rubberized battery cover that some have complained about, but I find to be a neutral aspect, however adding to the perceived durability of the device. I'm pretty sure you have seen plenty of pictures of it if you're looking for one so I won't include that.
Now, the sound quality. Whoever said that ATH-M50's don't benefit much from an amp must have been on drugs. I mean honestly, the difference between listening to the Total Bithead and the output of my computer is night and day. And my computer had a fairly nice Sigma-Tel HD Audio Codec that (I think) sounds better than my iPod 5th gen output. The main difference readily apparent is the clarity of the sound. Not to say that my computer sounded muddled, but this just sounds... better. Then, listening to it more and more, I realize that the bass is way better. By better I mean, it sounds more accurate. Before, it was just, bass, blah. Now, it sounds like theres a drum in my head. Its fantastic. One spot where thats quite obvious is in "Shadow of the Day" by Linkin Park. The bass beats in the beginning sound like someone's beating on my brain, which I like, of course I realize that some people may not like that sound. And its not as sloppy either, much cleaner and refined.
The mids are coming through cleaner now, and overall its hard to tell a huge difference in the highs, but they do seem a bit more transparent. I think the bass clarity though really helped to clear everything up and made the most difference in the overall SQ. Also, I have tried the "crossfeed" switch, and I find I can't tell much of a difference...
Not a review, just a first listen.