The spec sheet for the monoprice cable shows that the tip shoud be XLR pin 2 (instead of 1 like mine). That checks with the Yamaha schematic, so I resoldered the XLR end of the cable. Unfortunately that didn't do the trick and I'm still without sound. Measured the power cable hot and neutral wires just as they enter the unit (before the switch) and get 125VAC when switched off, dropping to 1.5VAC when switched on. The transformer has no hum or vibration at all, and there are 0V at the main caps and the rectifier bridge.