McIntosh MC206 humming

I just added the McIntosh MC206 amp to my Yamaha RXZ7 and now I have a hum coming through the speakers when the volume is turned down. Anyone know why this is happening? It did not happen before when I was using the internal amp on the Yamaha. Thank you

Possibly a ground loop. One way to check is if the Mac has a 3 way plug, plug it into a 3way to a 2 way adaptor without connecting the ground wire and see if the humm resolves.

Thank you so much blackraven! That was it. Works fine now the hum is gone.

Glad I was able to help!