Tube rolling LTA MZ3


hi,
wondering if anybody has done any tube rolling with a LTA preamp? Just got one, my sickness immediately makes me wonder if I can make it even better! Anybody have ideas on weather the 12sn7 or 12at7 position would have the most influence on sound?  For me, (in my system, my ears) this pre is an upgrade from Pass Labs XP12. So much more dynamic and engaging.
thanks for any perspective, Ted
caglioti
Have rolled NOS Mullard 6201's in place of the Genalex 12AT7s it shipped with. Smoother, less grainy but keeps the detail. Did not like any of the 12AU7's I tried including some NOS Mullards and Brimars. System seemed a bit lifeless.

Thanks to the suggestions here I got a pair of SIEMENS E80CC / 6085 for my MZ2.  Significant improvement over the GL’s that LTA provides.  Replaced the RCA 12sn7’s that LTA provided with a pair of GE’s and I think I prefer the RCA’s. Just got a pair of Sylvania 12sn7’s this morning.  Haven’t tried any of my VT-231’s yet.  Awaiting delivery of a pair of 1950’s Sylvania 12at7’s.  

I have tried a few different sets of RCA and Sylvania tubs, both 12SN7 and 12AT7. For me, the most noticeable improvement came when I swapped in a pair of 1957 Sylvania chrome dome 12SN7s. These tubes seem to add some sort of holographic pixie dust, and they are as extended as any good SS circuit. I continue to play around with the 12AT7 tubes looking for magic, but I’m sticking with these 12SN7s until they die. I actually bought another pair of Sylvania chrome domes, but this 2nd set is from 1960, and I fear they may not be the same (I don’t look forward to the day when I find out).