so this is a fun one... I was listening, had some problems recently with channel hum but resoldered all the grounds and replaced a few wires and it ran good as new for a while, but then earlier today I heard a loud pop in the right channel and it stopped outputting sound at all... after a little while I turned off the amp and turned it over, and one of the heat sinks on the Speedball was still hot while the other was cold. I replaced the wires and resoldered every joint not by the inputs or power supply, and the channel was still out and the heatsink cold. I think I got some wire backwards, though, because now the right channel was outputting and the left was silent. the headphones aren't the problem by that and by me testing them from my phone, the DAC isn't the problem (tried other cable & other audio source (monitor instead of DAC)) the tubes aren't the problem because I've retested with every tube in my collection, and at this point I don't know what else could be the problem. I'm worried the transistor blew out or something (can they even do that?), but lost my instruction PDF so can't remember the voltages/resistances to expect across components and terminals. where I have it now is that the signal is still only out of the right channel, but it is somehow quieter than before (I did move the cable from the top terminal to the bottom on the station by the power tube, but that shouldn't create THIS large a change in impedance/resistance, right??). how in the heck can I troubleshoot this?