The HeadRoom Total BitHead is a remarkable product. Not only does it offer a good performing DAC it can also function as a portable amplifier with crossfeed capabilities. The BitHead provides excellent performance at a reasonable price point that cannot be overlooked. You can get a brand new Total BitHead for only $149.99. At that price it is a total steal well worth the money for anybody wanting good sound quality for music.
Compared to most sound cards available today this is a decent upgrade, but will not provide good performance in games because it lacks all of the technology behind in-game positional sound.
The BitHead can drive pretty much all of the headphones on the market today reasonably well. The synergy between my Sennheisers and the HeadRoom Total BitHead was really good. Because the BitHead is so versatile it is great for use on the move with both a PC and portable DAPs. The sound quality increased exponentially when using the BitHead to drive my HD 595s instead of just right out of my Cowon DAP. The difference in sound quality was remarkable and made it worthwhile listening too.
When getting into headphone amplifiers you need to consider whether the gain in sound quality is worth the trouble of carrying around some excess bulk. I think that it is worth it with the BitHead because it is easy enough to carry around compared to the massive rise in sound quality.