On or Off

You have an on/off switch? Wow! My XP-15 phono stage doesn't. The only way to turn it off is to unplug it. I'm guessing it's meant to be left on. 

Pass always sounds better off to me. 

🤣

Just a joke people.  Commentary about readers who only read the headline and not the OP.

I leave my Pass pre and Ayre phono on but switch off the Pass amp but try to give it at least 30 minutes warmup.

On for better sound 

I reently bought a used Pass Labs XP-17 phono preamp.  It too only has an on/off switch on the back.  I called Pass Labs and was told to leave it on all the time.

On!

Mike

i have a pass amp also.  the manual is not specific about leaving the front panel switch on in addition to the rear switch.  

i do leave the rear switch on but turn off the front panel switch after listening.  

I always left my Pass pre on unless I was was leaving for more then a few days or a chance weather could cause a power outage or surge.

Official manual:

https://www.passlabs.com/wp-content/uploads/2020/12/XP-22_om.pdf

"Leave it on or turn it off: The product is designed to be left on all the time. The
exception to this might be a case where the preamp will not be used for an extended time - in that case it can be turned off.""