Preamp arrangement question

I recently added a Rotel RMB-1075 multi-channel amp to my RSX-1057 to increase output in each channel driven from 75 watts to 120 into 8 ohms/20hz to 20khz. What happens to the amplifiers inside the RSX-1057 receiver? Do they know to turn off or do they remain on and contribute to the overall output? Am I actually putting out 120 watts/channel + 75 watts/channel? If not and they remain on, what happens to the current they are producing? The owners manual does not address this. All of the interconnects are properly installed and the loudspeaker wires are now connected to the amp outputs. Just curious what is actually going on inside the AVR with this arrangement. Many thanks.
When you use a receiver with an outboard amp, the receiver's amps are bypassed. On the back of your receiver there are pre-outs. RCA cables are run from the pre-outs to the inputs on the amp therefore bypassing those amps in the receiver. Then you must connect speaker wire to the amps binding posts and run to speakers. Your amp will be putting out 120w/channel. The unused amps in the receiver will sit dormant if there is no channel to send it to. Many people use only a 2 channel or 3 channel outboard amp to power the fronts or front three(L-C-R). In these cases, only those channels are bypassed in the receiver and the receiver handles the rest.


Thanks for the very well written explanation and quick reply. That answers that !!