Pass labs poweramps

Popping is usually a sign of excess DC on the line
i experienced this recently with a tube amp .
get it checked out .
what model,  how old  is it.

I didnot read every response ,it went from popping to a clicking.
unless you know whatelse is in the chain   Impossible to give an accurate diagnosis.

A model would be most helpful. It could be a number of things. Nelson is extremely easy to reach directly. His email address is pretty easy to find. It's usually in the First Watt owners manuals. 

Thanks for the info the is X260. 8 monoblocks

Pass is always happy to talk you, you should just call them. They'll answer your question and make you like the company better.