I have a HSU StF 1 in my bedroom and the amp went bad. I ordered a new amp from PE Dayton SA100. Hooked it up yesterday and sounds great. However I notice a low humming coming from the amp. The humming is there if I unplug the rca and even if I turn the auto switch to off. It is a low humming but annoying because it’s in my bedroom. Any ideas or should I call them and get it replaced? I’m wondering if they send another one if it will do the same thing.