[Peter Daniel]

The important aspect about sharing a single transformer and common rectifiers per two amp channels is power star ground.

While you could simply run PG+ and PG- (ground) wires from rectifier board to each amp board, in some setups hum problems were reported and presently I always use star (power) ground in all my amps.

I simply achieve it by connecting output grounds (OG, on the opposite side of speaker wire connection) with a 14ga solid core copper wire.

The center of that wire is my power star ground and both PG+ and PG- grounds from rectifier board connect here. In the picture below the connections are so short that I used single runs of wire, normally I use two wires for both PG+ and PG-.

Please note that power ground is also directly connected to the chassis.

I specifically refer to it as power star ground, as signal wires from RCAs are not connect directly here. They connect through separate traces on PCB to OG (output ground) pads.