Phono Stage Cuts Out

Thanks alot for your responses. It's interesting or perhaps simply coincidence that this issue started when I changed from the stock power cord to a very expensive Virtual Dynamic PC.

If it goes dead silent in one or both channels with no other signs of trouble, it's likely to be a relay that is malfunctioning. Not likely to be a capacitor problem. This fact is not a lot of help to you, because you will need to have a knowledgable tech fix it.

Total guess, but if just turning the power off and allowing the capacitors to discharge settles the problem, it could be a capacitor. Since it is not effecting anything else that should at least limit it to the phono circuit. If you have a voltmeter and a schematic you should be able to figure out what voltages go where.
My son had a similiar effect in a sunfire preamp, it would not let him change venues(CD, phono, etc.), till he followed your example. He decided to let it go to a friend who is an electronic tech and could take care of it. Never learned what was wrong.