Using RX-v773wa to drive 4 - 80wpc amps sections on a NAD T754 with bad surround pre-outs. The Yamaha L and R pre outs are "Y" to two channels, each, for the four stacked main front speakers. This was done to keep speaker loads to 6 Ohm each per pair as each speaker has own 80WPC amp. The NAD will cost $400 to repair so owner wanted to put 4 of the six amps to work and use the Yamaha for center and surrounds. The owner still favors the 45lb toroid x-former NAD sound over the Yamaha but will use the Yamaha HDMI to upgrade his video suite.
Sounds very good but now chasing faint ground fault noise when NAD connected to Yamaha in any pre-out configuration, either single or multiple. YPAO gave three different gain settings depending on config with the "Y" cord having higher gain. This may account for the reduced pre-out voltages when driving two instead of one input. The next week will determine if owner will keep this configuration or look elsewhere. The two amps per side, a quasi bi-amp, does sound a bit better as opposed single amp and parallel speakers per side.