I know enough about this stuff to be really dangerous, but wouldn't a passive output sound better than an active one with all the opamps? I did something similar with my Lite DAC-AH and it sounds much better to my ears. Of course, the caps I used cost more than the DAC itself.
In any case, I'm moving ahead with the ASE-Audiotuning mods to swap out the stock Yamaha receiver (YM3623) and NPC filter (SM5813) on my D/AC-800. I'll report back when they've settled in.