Audio Research I/50

what do you mean by "the more contemporary i/50 styling" ?

This was taken from the I/50 owners manual.

Vacuum Tubes
It is recommended that you replace the vacuum tubes of your I/50 in sets. All of the tubes in your amplifier have been matched to have similar operating characteristics, to provide the best sound quality and reliability. 6550WE tubes should be replaced at approximately 2000 hours. 6922 tubes should be replaced before 4000 hours. Upon replacing a power tube or tube set, the I/50 must be biased by a trained technician to ensure proper operating values.

It seems like the amp can’t be biased by the owner of the amp. If that is true that would definitely be a dealbreaker for me. Just sayin’.
 

i read somewhere that it has an automatic bias.
its a bit hard to believe that you cant make a bias.
any way i asked a friend of mine, a experience technician in those amps, to check this subject.
i agree that its a bit bother, since from my experience tubes bios should be checked from time to time, even before replacing.
this subject must be checked.
2000 hours is not so much to people that use the amp frequently.
"If your amplifier is getting regular use (2+ hours a day), you should at a minimum check the bias every 3-6 months."

found this:
"Like all modern amplifiers from Audio Research, this one also has automatic bias adjustment, which makes living  with a valve amplifier much easier".
but still, i  would like to have an option to check and bias it by myself from time to time.