A picture from the '2031' days...
H1 discovered this combination and went on and on about it (in style, as only he can do). So I tried it and found he was right. Somehow the two different driver tubes complimented each other perfectly and produced a rich sonic orchestration, in the Elise.
I know it sounds crazy to use different drivers, but all who tried it, really liked it.
One FDD20 (requires adaptor and external 12v heat) and one ECC31 (requires adaptor).
In the picture is the FDD20 in foreground and ECC31 behind. Powers here are the Mullard 6070's. (I would suggest socket saver spacers on the 6070's as the do run quite warm, the spacers keep heat away from the amp innards).
My amp always suffered from heat build up, some said thiers didn't. We think the transformer in 220v units had to work less hard than 120v units and generated less heat...?
Anyway...have fun! Elise is a nice sounding amp, 2031 or via the default compliment.
Cheers...!