since you guys are talking about auxes not working, I noticed that it is a "pair" of outputs not working, and WK is probably correct in that it is an OP amp. The OP amp handles two channels of audio, so this would also explain the signal level showing properly but no audio. The displayed levels are not likely getting their signal for meter reading from the output of the OP amp but instead, before the OP amp... just sayin....
Dan