Regarding the Total Bithead, a couple of years ago I bought and returned one.
I just wasn't that impressed with it. The SQ was fine. It could certainly drive my HD-650's better than an iPod. But the tubes of the MKII add a richness (distortion - whatever!) that the Bithead didn't. A rich creaminess that I just love. Some hate it. Different strokes for different folks.
But the biggest problem I had with the BH was that it was extremely susceptible to GSM cell-phone interference. At the time I had a BlackBerry, which was in constant communication with the network. I couldn't put the 'Berry within 6 feet of the Total Bithead, else it'd pick up the dit-ditty-dit ditty-dit-dit-dit-ditty-dit GSM signals in the headphone output. And heaven forbid I got a phone call...
