We built a DAC board for sub/center out. Something's not right with the digital signals. It almost acts like it needs another stage of buffering. When connecting it to the I2S output on my Rio it outputs terribly distorted sound unless I bridge the MCK input to ground with my finger. Then it sounds pretty good. There's nothing wrong with the I2S outputs. Those were tested and provide pristine sound through a P-3A DAC.
It turned out pretty small at only 11/16" x 1 1/16". The output is selectable as sub or center via a jumper. No time to work out the bugs at the moment. Hopefully soon. Here's a poor quality pic.
Stu