Thanks for replying, guys.

I have checked all of the obvious software things ... equalizer presets are where they were before. Volume is not muted (as far as I can tell ... there doesn't seem to be a mute function on the remote, and I don't have the cell phone mute wire hooked up as far as I know). Hijack's dynamic volume adjustment is turned off.

Here's a software possibility: Could the unit be in the "hushed" mode? Which lowers volume but doesn't mute?

Before this happened, one other thing I installed was the charcoalgray99 web interface (which is awesome). I also edited config.ini (using JEmplode) to add the [output] notify=1 lines at the bottom. That all went well. However, when you bring up the remote control on the http interface, it has a Rio remote, which has the hush function on the play button. Could I have hushed it from there without realizing it? I don't have an actual Rio remote, I have the Kenwood remote, which doesn't have the hush function.

Is there a diagnostic I can do to find out if the unit is in hushed mode? There is no "h" on the front display, so it shouldn't be, but who knows. If so, how can I unhush it without a real Rio remote (yes, I know, presumably the same way I hushed it, hehe). Of course, I don't know how I did it.

Just for kicks, I tried various edits of the config.ini file, including mute=0, mute=1, hushpercent=0, hushpercent=100. None made any difference.

Anything else I can try?