Sub $350 you should seriously consider the Audiosector. You might also consider the VALAB DAC (which sell on eBay under Vintage Audio Labs) for $180. I have seen a used iRoc DAC go for as low as $485 recently.
One other to consider is the Audio Magus MagiDAC. Looks good on paper.
One other to consider is the Audio Magus MagiDAC. Looks good on paper.