I'm glad to hear you tracked down the hum. I was hopeing this was the problem and not a poorly wound Tx. I'll ground my pot tonight. I thought I had the issue of isolation between the chassis and signal ground resolved, but there is still continuity. I thought the volume pot was the culprit, since I could lift it off the chassis and get infinite reistance. I need to see if a wire strand is causing the problem.
I'm really surprised that ESD killed the 2540 that easily. Mine took a direct hit when checking voltages. Let's just say I about wet myself - didn't shock me, but did get my attention. Do you need a couple of 2540s as spares? I could drop a couple more in the mail if you would like.
Are you going to do the amps next. I'm really excited. This whole process has been much more than I could have imagined......Colin