Mcintosh Amp issue?

Hey there, the wires to my amp were butchered so I had to solder them back onto the connector from the speakers. the power wires and ground wires were all still connected, so that's all done. However I've never had a subaru with a mcintosh system before and when I had everything plugged in, it worked totally fine but from the mcintosh amp theres like a buzz or hum. I was thinking maybe it's a internal fan? However I don't feel comfortable putting the seat back down till I know what it is, or if it's a wiring issue on my part. Or aybe a issue with the amp? any advice would be grateful!