Take a look at the Asus Essence One USB DAC. At $599 list and an $899 version with MUSE01 opamps, it's a great bargain with high end sound without the high end price. All versions have replaceable opamps for opamp rollilng. I use it in conjunction with a dedicated music server and swapped out the stock opamps some precision audio only opamps and finanlly get sound that reviles or equals my CD player when playing back lossless formats such as flac. http://www.head-fi.org/t/542563/asus...dac-cebit-2011 is a thread that talks about this DAC and how it sounds with various opamps.