Should I leave an Old Krell FPB 400 cx on all the time?

Use standby mode unless you don't expect to be listening regularly or are leaving for vacation or a long business trip.

Got 1 to 2 years left before recapping thats why I was wondering to milk a few extra years if turning it off completely will extend life. 

I keep my old Belles 400A on all the time. It has no stand-by. Luckily, for start-up and shut-down for the rest of the system, I have an ifi Mini Tube2 between the pre and amp that disconnects/connects the connection when I turn it off/on, but the amp stays powered 24/7.

While not in use, it cools off and stays cool. I’ve watched my electrical use and no change after many months of doing this. When I start-up the system, the Belles is also ready to go.

As this amp is over 30+ years old, I’ve been told there is less strain on any old parts to keep it on vs turning it off and on daily. So I do. 

Standby is the way to go,  turning the amp totally on and off can stress the caps more than just leaving it on or partially on (standby).