Getting a variable buzz from my speakers. System is two years old. Mac mini, halide dac hd, FP III, Paramounts orcas and subs. Cleaned tube pins (p&p 5 times). Disconnected Mac Mini, Dac, sub Amps. Don't know if this helps but noise not present with FP III turned off. Turned FP III over and all I can see is cap on OD3 socket appears to be bulging on one end. Only recent change is Mac Mini but unplugged and disconnected all of the related computer equipment. Help