tube amplifier auto bias- accurate?

I am sorry to disagree with everyone so far. I have owned numerous tube amps from low cost to very expensive. Some auto biasing and others not. There is NO substitute for having your amp biased by a professional with a scope. None.
Ask a tech and see if they don't concur.

Ed your wrong on this one.
Only way you can bias a tube amp correctly is to use a scope and a dummy load. A440 cycles when it starts to clip you then adjust so the cross over notch disappears. You have to look at the wave form! If a manufacturer says its autobias its either full class A or if its not class A they are lying to you.

Eldartford,
In my opinion you are one of the most knowledgeable here on tube amps and often find myself silently nodding my head to your conclusions. You have provided excellent insight to both the novice and expert. I agree to your last sentence in this thread…So which way would you rather have your tube's biased? :-)