Tube rolling my preamp with 6922EH

Of course: The some of the best 6922s(CCa, E188CC, 7308, E88CC by Telefunken, Siemens, Amperex, Valvo) DO have gold pins, but they(the gold pins)won't make any sonic improvement on a tube by themselves. Step up to a matched NOS pair of one of those variants in your preamp and the difference will amaze you.

"Warmer" and "darker" are colorations and exactly the opposite of "transparent". If you want "warmer" sound and less highs, a pair of NOS Mullard, Ediswan or Brimar tubes(British manufacture/coloration), ie: (http://www.upscaleaudio.com/product.asp?itemid=282&catid=42) will provide that without a sacrifice in imaging or soundstage.

I should have mentioned: With regards to the "focused bass" you're seeking- That's usually more a function of the amp/room/speaker/cable/interconnect combo. Of course the preamp plays a role as well, but the pre and tubes can provide as accurate a signal as possible, yet the bass end up sloppy via a lack of synergy elsewhere.

These sites have some good info: ( https://www.tubeworld.com/6922.htm ) (http://www.audiotubes.com/6dj8.htm) (http://home.att.net/~chimeraone/6dj8sound.html) Looks like the tubeworld URL might have to be copied and pasted for some reason.