Hello I'm new to this forum and have a question.

I have a rr2150 receiver currently running one set of speakers. My question is what would be the best way to connect an external amp and another set of speakers and using the rr2150 and the external amp simultaneously? I appreciate any advice on the subject.

Use RCA Y-splitters, connect the single end out from the pre-outs left and right, feeding one of each of the dual ends into an external amp left and right and the other of the dual ends into the main in of the RR2150 left and right

Save the money on the external amp and just run wires from the B-channel of the RR2150. It's designed to run two sets of speakers at the same time.

But read the addendum for restrictions on driving two sets of speakers.