I got 4 of these for my TSL 602 combo:
http://www.groovetubes.com/NAMM2004_04.cfm
from
http://www.kcanostubes.com
I really dig the tone of these tubes, smooth and just great tone (hard to explain). I also put in a celestion greenback 25 in one of my mesa 1 x 12's and that was a good touch too. I'm able to record at relatively low volumes with this setup and get a great tone.
Cheers,
Lumen