I don't find myself in a bind like this often, but I installed a quad of NOS Valvo(Hamburg, Germany, Mullard Made) EL84 power tubes in my Crate Vintage Club 50 amplifier(2x12 Version), and everything worked great for a few minutes, but I got greedy and turned the OD channel volume very high, and the instant I did that, the amp cut out completely on both channels. It's never done this before, through several tube changes. It powers up, both switches light up, and the fuse is intact, I've checked all internal connections for breaks or loose connections, and I've checked all the tubes, which seem to be fine and all light up normally. When you flip the standby switch, you don't get any sound, it's just dead. The only thing I haven't done is get out the multi-meter. I'd like some outside opinions on this before I start systematically checking every resistor and cap. My first thought was could it be a screen resistor? Of course I didn't bias the amp, because I've never had to before. I thought this was a cathode bias amp, as are most EL84s. Any ideas are appreciated. Thank you!