After more than 2 weeks i must say these tubes shine. and when i put on the reflector After getting sued to this the music seems to have gotten Duller (relatively speaking as i used to love this before)
I would wholeheartedly recommend them over the reflector (next best) and the SED (after both of the former...not having heard other 6l6's)
The Bass is so much more articulate and the double bass is to Die for (Kings of bass- Gary karr, Ray brown - producers cut) the lower end harmonics have never been more clearer...and with no loss of midrange purity. I played the Chesky's ultimate demonstration disk yesterday night and was in raptures during Ms Pidgeons voice...which is not my usual favourite.
Bolero, the dumper tube has no sonic impact (or so i believe) as it only regulates the current initially so as to preserve the life of the power tubes. so would not have any impact
I really dont know enough about the KT77..they would be good no doubt.
Regarding Leben sound, from my personal view, the tonal shifts will occur with any tube .. but you will not lose the slam and the power expected out of an SS which the leben brings about along with the micro dynamics and the tube like immediacy & fluidity across the full range....and thats a pretty unique combination (of course which would mean compromises with what an SET lover would expect)