[Leadfeathers]

I've read the thread from June '09 or so discussing power tube preferences of RM9 owners, and see the usual suspects represented: EL34's, KT88's, 6550's.
   I've noticed over my couple years ownership that the sound characteristics of my 9 are also strongly affected by the choice of driver tubes, both in brand, and type.  So I'm interested in the combination of the power tube and driver tube some of y'all are using, and what are the sound characteristics you end up with.
  I'm currently using Tung-Sol 6550's as power tubes, and am now in a tube-rolling mood with the drivers;  had some Tesla ECC88's until my recent amp difficulties, when I replaced them with GrooveTube 6922/6DJ8's.  Found that combo to be a little boomy in the bass.  Now I've gotta root around and see what else I've got that I can try.
  So, what are you guys using these days? 

[Ericus Rex]

By 'drivers' are you referring to the front pair or back pair of miniatures?  (just want to make sure we're on the same page)

[Leadfeathers]

Front pair.  This is the pair I've rolled since I've owned the RM-9.  Is that the correct terminology?  And what are the rear pair called?    (I'm a bit rusty on some of this; haven't spent too much time tweaking for about a year......)