I think the advice being given about contacting Pass Labs before powering up is sound. Not being familiar with Pass equipment, is there any current limiting circuitry in them? I have a Mark Levinson ML335 that's been boxed for 25 years or so. When I asked a similar question here about powering it up, it was recommended I send it to a shop to have the capacitors checked first. I found a shop in Austin (Pyramid) that I'll be sending it to BEFORE I put it in my system.
Incidentally, I had occasion to visit my daughter in Austin recently so took the opportunity to visit the shop. I was very pleasantly surprised at the facility and evident expertise available.
Good luck waking up your amp and as always...
Happy listening.