Selectable B+

[sliberty]

Flipping the Standby won't really help as it comes after the rectifier. I would probably power down.

[M Fowler]

I suggest powering down but admit I've flipped the switches during playing

[surfsup]

RJ's Eagle Supre has the edcor tranny with dual HV. I have this installed in mine which was changed from his schematic into a completely different amp (cascoded input, Mosfet CF, etc) The higher voltage offers slightly more headroom and is a touch brighter. I have a switch to break out my second stage cathode bypass cap. I can tell there for sure because with the amp cranked the headroom is noticeable but not much from the lower HV option. I switch with the amp off.