After about 30 seconds of playing music (CD's), a loud hum is heard and the music stops playing. I'd like to isolate/identify the source without having to dismantle the entire system. Any insight would be greatly appreciated. I currently own an Odyssey Stratos Amp, with Van Astine Ultra SL Pre-Amp and an Insight DAC; and a OPPO CD player used as a transpot. Thanks.