I am not experienced in this area, but there are no places within a 2.5 hour drive to take this thing to. If you think you can help, here's what I've already ruled out. Channel 2 is working great. Analog or digital, the inputs are lighting up in the expected way. I have tested all other possibilities in the signal chain and it is definitely the channel. Nothing lights up at all when I plug a mic in, and obviously I'm getting no input either. I've looked inside and don't see any obvious problems like severed connections. I switched the tubes and this made no difference, so I know it's not the actual tube. Any thoughts on the next angle?