124 build pops when you turn it off.

[gary sanders]

Just started doing this.If you turn stand by off first it doesnt pop.

[Structo]

Probably just the switch has arced and damaged the contacts Gary.

I switch my amp off the same way, just the power switch.
I leave the standby switch on play since that has DC on it and I figure the less I use it the better.

However, I do use it when I warm up the amp for about 20-30 seconds.

I also put a .001uF ceramic cap on my Standby switch to help the pops.