Hi Joe,
One other thing, the E288CC does not seem to be an equivalent of 6922. It has different electrical characteristics, with the E288CC drawing about 50% more heater current, and drawing double the anode current. It might be fine, or it might damage your preamp if it draws more current than it can handle. I recommend checking with conrad johnson to determine if it is safe to use in the ET3 SE.
example 6922/E88CC:
heater current (If): 300mA
anode current (Ia): 15mA
http://www.mif.pg.gda.pl/homepages/f...09/e/E88CC.pdf
example E288CC:
heater current (If): 475mA
anode current (Ia): 30mA
http://www.mif.pg.gda.pl/homepages/f...0/e/E288CC.pdf
Anthony