Email them. I’ve biased amps for years using the red-plate method. Dim the lights. Power up. Adjust so that the tube anodes (plates) just start to glow red. Now back off a little so the glow fades away. Check current. Recheck current and bias adjustment after 30 mins. You can tweak it back a little and compare by listening if you want to run them even cooler without sacrificing SQ.
