I looked back several screens to see if this had ever been raised and couldn't find anything.

Are there any symptoms to listen for, when an amp's tubes are going? Or do they just quit? Is there anything I'd be able to look for just by giving them a visual check? Everything seems to be working okay in my Peavey, but it's just something I'd been wondering about. If it's any help, it has 3 - 12AX7's and 4 - 6L6GC's in it.

Any help would be appreciated!