Winchell,yes a DAC can make a tremendous difference in the sound of your system. The Benchmark will sound much better than the Adcom. For around the same price I would suggest you try to Audition a Bel Canto DAC II. I believe it is better sounding then the Benchmark and also is very immune to jitter so you still get great sound with just an ok transport. Either a demo or used one should be in your $ bracket.Hope this helps. There has been posts on DACS in this price range recently here on the GON,look them up I think they would be helpful to you.
