accidental power down....any damage???

Many amplifiers do not like to loose input power from a preamplifier when powered up. Some put out distortion, some may hum, some can go into oscillation.

This is usually bad for loudspeakers. Many amplifiers have
protection relays, and will clamp down or mute if DC is present in the output stage.

I would check your speaker panels, and if you have any fuses, check them also. I am not sure if the Pass has protection relays, but it probably does.
Check your woofers also, especially if they have fused protection. Make sure that they are working.
Perhaps nothing happened, as the first response mentions.

But I have heard many amplifiers, tube and solid state, make some real nasty noises when loosing input signal.....

Check out your speakers, hopefully nothing is wrong.....

Best, Bill M.

I doubt if anything bad has happened. I have a bi-amped system
using a pair of quicksilver KT-88 monos for mid & high freq.
our power being supplied by the electric Company is so undependable it has gone out while the system was playing and before I could get to the power switch(seconds) the power came
back on. NO DAMAGE - however that will shorten tube life
As a result I went out and bought 2 APC battery back ups
It never has been problem since

Thanks guys for you input. Thankfully, I powered everything up this afternoon, and all was fine. Just got nervous because I know its a big no-no to shut off power to the preamp while amps and speakers are powered up, and I am so careful with all my gear. She just didnt know, and she will probably circle the room from now on to avoid getting within 10 feet of the system. Being new at tube equipt, I wasnt sure if anything could have gotten damaged, but it must have been my imagination that it sounded different last nite afterwards. Thanks again to all.