Svetlana vs. GE tubes for conrad-johnson


About 2 years ago c-j changed the source of the 6550 power tubes in Premier amps from the GE n.o.s. to Svetlana 6550-C. If you have owned a Premier 11 or 12 and have compared, what's your impression of the different sound these two tube sources produce? Any other good choices of tubes for these units?
k525