Depends on the amp. If the current one connected has a preout you can just use that second amp but you won’t have receiver tuning capabilities to the speakers hooked up on it. If both amps are higher end and run 2/3/4 channel mode you can run half the rca’s And still get signal to all channels on each amp but you’ll still be missing receiver level tuning to the channels that aren’t rca direct to the the receiver. Most thorough option is to get a dsp. The Dayton one seems to have a strong value and benefit buzz.