I am going to use it. A small R-S unit. When closed it shorts the output side of the caps to ground. I think I put it in the original schematic( or at least half of it ). When open it is about as far as is possible to have removed from the audio path. What little capacitance is added is well overshadowed by the drive capability of the plate load/output buffer's drive.It isn't a big deal, just requires a turn on sequence if omitted. It also make linestage tube rolling easier, as you can short the outputs, and power off the linestage w/o messign with the amp.
regards,
Douglas