Sirspeedy, I would be suspicious that the CD player is making either RF, DC or both. I'd pull it out of the system altogether, as if it is RF, well, that stuff can get in everywhere!
Given what you have told me its *not* the tone arm that did that.
Alternatively, your preamp could have been giving you fits all along, with the symptom masquerading as something else. First thing I would do would be to run the system with no digital at all and see if it works. If yes, let it play and see if it still pops. If not, then you need to see if the amps/speakers are OK. If they are, then you need to talk to the manufacturer about the preamp.
Given what you have told me its *not* the tone arm that did that.
Alternatively, your preamp could have been giving you fits all along, with the symptom masquerading as something else. First thing I would do would be to run the system with no digital at all and see if it works. If yes, let it play and see if it still pops. If not, then you need to see if the amps/speakers are OK. If they are, then you need to talk to the manufacturer about the preamp.