I realize you already have a DAC, but if you would be interested in getting the best DAC/amp combo available, check out the Resonessence Invicta. Yes, it's pricey ($4000) but considering that you have both a world class DAC and amp together in one unit, it's really an incredible value. And it sounds amazingly good with the HD800 (others have commented on this too). I've had my Invicta for a long time, and continue to appreciate it everyday. The company strives to make their products as immune to obsolescence as possible by providing software updates that allow such goodies as differential (balanced) headphone drive, DSD playback via the SD card (which itself is amazing), etc.