ok so a while back i posted that my infinity 7541a 4 channel amp was cutting out and making poping noises well the other day i decided to hook it back up after a coupple months of no use and to my surprise the amp worked and played music as normal. i have no idea what could have caused the problem but now when i power up my system i can hear my 4 channel amp powering up through the speakers. im not sure exactly how to explain the sound almost like a hum but then it goes away after about a second. iv checked my grounds and power connections, any other suggestions?

 

try redoing the ground
i would try a bench test with it