I get heavy distortion at mid-to-high volumes on low-impedance headphones, but the line output works pretty well. There's still a bit of hum but it seems to be at acceptable levels. I had reconnected feedback when fixing the line output problem. Is there something else I could try to reduce this horrible distortion?
changing the headphone out feedback pots from 25K to 1K just seems to decrease volume - no effect on distortion is detectable.
of course, when I pick up my oscope probes, I can have a better look.. 20Hz, 2KHz, 20KHz sinewave input should help demonstrate clipping, right?