i recently bought one of these and it sounds great, howevever, sometimes when i turn it on it on the speakers will do this pulsing thing that sounds like a very fast, inconsistent, loud heartbeat while the speakers move in and out than it will stop and will only sometimes continue to happen every few minutes while the receiver is on. other times this will happen, so i will try switching from phono to the FM receiver, and when i go back to phono it isnt doing it, but the sound coming from my phono source is very quite and weak. anddddd than other times i will turn it on and not have a problem at all, someone please help me because this is extremely frustrating!