ARC ref One MK II Tube Upgrade

I'm about to replace the stock 6922's in my ref one and I'm curious about the options and peoples experience with other tubes.
The rest of the system is:
ML front end - #37 transport, #360s DA
Krell FPB 350mcs
Transparent Ultra XL balanced interconnects as well as speaker cables.
Shunyata Hydra & Python power cords for ML
Thanks in advanced for the help.
On my reference one i am using 8 6922 amperex from u.s.a. and the unit sound pretty good.If you want a warmer sound you could go with amperex bugle boy from Holland ( new old stock). it is a matter of taste.i encourage you to go on dicussion trail regarding best sounding 6922... an make up your mind about the sonic signature your are searching for!!!
Thanks. Anyone else?
So here goes on the 6922's.