I've had a really annoying problem with my McIntosh C2300 preamp recently, but only in the phono stage of the preamp. Very often, when I finish playing an LP and lift the record off the turntable, I'll hear a really loud, insistent thumping sound coming through my speakers and visibly shaking the speaker cones. It's really, really loud and I've gotten in the habit of lowering my volume before taking the stylus off the record for fear of damaging my speakers. The only way the noise stops is if I turn the preamp off. It only happens in the phono stage. For what it's worth, I'm running vintage Mullard tubes. Any idea what this might be? Is it static? And is there a way to prevent this from happening? Thanks for any suggestions.