Re: Just a pretty picture
I've biased a lot of amps by ear, and my favorite way of doing it is to turn out the lights, use a glove, a mini screwdriver, amp chassis out, and look at the tubes while tweaking the bias pot.
I hit the open strings or chords, hearing how the amp reacts to my biasing, and stop the minute the amp sounds spectacular. And seeing the tubes glowing in the dark tells me how healthy they look.