I am getting a motorboating sound from my main speakers- ostensibly the source would be my Adcom GFA1A power amp. Other system components are an Adcom GFP1A preamp, Denon DCM370 CD player, and Audio Alchemy DDE 3.0 DAC. It will occur at random intervals, and occaisionally manifest itself as a burp or a long stream rapidly rising in pitch and speed. This is very scary for me, because I have no idea what the problem is and if it could be potentially damaging to my main speakers or other system components. I would be grateful for any help. Thanks.