Sounds like you have DC voltage on the PV10's output to me. Usually you can tell by looking at the speaker drivers from the side but with Maggies, I guess you can't do that. You could check the output jacks of the PV10 with a good multmeter and see what DC voltage you have. If it is anything more than 5mV, that is your problem and will definately make your NAD shut down. A lot of tube preamps have excessive DC on the outputs and SS amps hate that. We couldn't get a Cary SLP98 to work with a Classe CA200 for the very same reason. The Classe would go into shutdown immediately. To fix the problem, we got rid of the Cary.
Arthur
Arthur