Calling help for Lamm ML2.1 biasing!

Here's the top of an ML2, which for these purposes, is probably identical to the ML2.1: 
https://thevinylpress.com/app/uploads/2018/08/lamm.jpg
I was trying to find something the other day and ran across a pile of literature from Lamm. In one piece, he talked about not letting the setting of plate current go higher than indicated at the risk of damaging the amp. 
If you have a question about the amps, there's really nobody better to talk to than Vlad. I would recommend an email to Lamm to set up a call, only b/c they typically don't take calls during the day. I think they also want the dealers to handle issues on the front line, but I've been dealing with Vlad and Elina a long time. 

Vlad urges that you buy a very high quality meter- a Fluke- which is spendy, but accurate. You should check the bias periodically and see if any settings have drifted. Also, Vlad burns in the "new" power tubes before sending to you but I usually wind back the current a little when replacing the big tubes and gradually feed them more signal via the preamp volume control over time, keeping an eye on the settings.
Some of this information-- like the requirement of a quality meter-- is on the owner’s page linked to above.
Enjoy your amps.

I don’t know how to answer that question. The unit I have is configured for US voltage which follows a norm and it is within spec. I have an AC subsystem for the main system that is depicted in part in the system shown here under my name. If you are asking if variations in mains voltage would have an effect, I would have to believe so; ditto, noise or other nasties on the line will probably be revealed, especially using highly efficient speakers (104db/meter in my case) that are most suitable for this kind of amplifier.
If there is something technical you want to know, the best source is Vlad, who designed and built it. He is a nice man to talk to if you get the opportunity.
PS: to the extent you are asking about biasing, yes they interrelate. But, variations in voltage are rare; the current setting needs to be adjusted over time to address tube degradation.