Separates is going to in most cases get you better power supplies optimized for the job at hand. I would MUCH rather have monoblock amplifiers located within 12”-24” of the speakers and an XLR balanced connection to the preamp. Depending on length of run and RF environment, you might be ok single ended RCA. You could get very close to this with Quicksilver amps and a pre at top end of your budget. What speakers are you running, how big is the room, how loud do you listen ?
Jim