I've had my 990 for a while but never tried the headphone jack till today. I pushed the mute button on the 990 for 3 seconds to change modes, plugged in my headphones via a 1/8 to 1/4 converter and no audio! I researched here and tried to change "CD" input off of upsample, but I dont think it was on it to start with and because I dont have any input on CD it doesnt respond to change of surround or stereo button presses.

Is there anything else to try? I've tried three sets of headphones and two different adapters, so I think its the 990.

Did the red light on the front panel turn off? (It looks like a speaker symbol.) If not, try holding the mute button down longer.

Yes it did.