Audio Research I/50

i also will not buy an amp that  can't control the bias , auto or manually, but i think that this subject still need to be checked.
i don't think you'll have to send it for biasing.
think that the meant is when you replace the tubes, let say after 2000 hours of playin, which to my opinion it's not much, it can be to me after 1.5 year, you can bias it using a technician at your place.
but, yes, if it like that ,it's disappointing. 
 

@mezzanine +1

We must have the ablity to bias by ourself or auto bias,it is bottom line.

Otherwise,the Tube drift,especially for the new tube. How we can ask the technician mutli times for the same issue? 

I am asking this point to Audio research and hopely they will reply me soon.

@mezzanine 

       I have a question for you. If the power tube 6550 bias is very stable. Is that to say, the tube is ok for use and not even near the end of lifespan?

I get the reply from Audio Research regarding I/50,

"Dear James

Summary: The I50 is not auto bias. The tubes should rarely need to be biased on this product but if it needs to be checked, the unit needs to be disconnected, turned upside down ,and the bottom cover removed, then there will be points to connect a voltage meter and read the settings. There is a small pot to turn with a plastic screwdriver that will adjust the bias. We are working on written instructions for this as well as a short video. Those will be available in the near future."

With my vt100 MK iii, we adjust the bias while the amplifier is connected.

Why for I/50,it need disconnected and do adjustment? I do not know.