Emotiva Stealth DC-1

Interesting review. The 503 is newer and uses a smaller audio board - also uses more SMD devices. The 501 uses different voltage regulation. The 501 can be more easily modified (upgrade op amps, caps, regulators). There is a very long thread of discussion on the 501 here:

http://www.head-fi.org/t/632413/teac-reference-line-ud-501-usb-dac-dsd

The Emotiva stuff is very nice for the money you spend on it. The sound is not harsh, very smooth. However, in my opinion, it can sound closed-in or dull. I’m sure the Teac 501 is going to sound different, possible with better resolution. Not sure how they compare. The 501 can be obtained used for about $600. It’s going to be hard to get better than either of these unless you hit the $1200-1500 area (maybe Bryston BDA-2 or Wyred4Sound).

The Emotiva DC-1 is almost exactly like the Emotiva XDA-2 dac, except the DC-1 is a fully differential/balanced circuit from DAC chip to output.  It also uses LM4562 as output buffers instead of OPA2134 (as is used in XDA-2).  The sound is going to be almost the same.  Both have same power supply and both use active I/V circuits for an AD1955 DAC chip.

If I was looking in similar price range, I would consider the Teac UD-501.  Isolated power supply sections for each channel and does not use active I/V (which does require some power supply current).  Teac is also fully differential/balanced circuits and does support DSD (if you're interested).