Preamp Tubes For Jolida

I have a new Jolida 1701A Hybrid amp(50W per channel solid state amp, with two 12ax7 tubes in the preamp section) It is excellent, and I'm looking forward to some tube rolling to see the differences.
With these tubes(12ax7, 5751, Etc.) how picky do I have to be with matching & balancing?? I am looking at a pair of 5751 triple mica RCA blackplates with tests of 40/40 and 42/44 with 32=min. good, and 50 as new. Just a matter of one wearing out sooner, or a sonic difference? Which is more important, the inner tube specs, or one tube to the other? and what tolerance(2%, 5%, 10%) is tolerable!
I assume that even NOS same date pairs should be tested for match & balance, they are pricey. Hope I didn't ask a book sized question, tried search & got nowhere. Thanks!!!

Post your question on the tube asylum at audioasylum.com for more responses. http://www.audioasylum.com/index.html

Well, I have heard from others that have the JD 202a like me, a full tube integrated that uses the 12ax7's, that upgrading the preamp tubes really doesn't make a huge difference in sound. So, I assume for your hybrid, the difference would also be very minimal. On another note, you should not be too concerned with the longevity of the 12ax7's, no matter what you get. The stock tubes supposedly last 5 or 6+ years under normal wear. They aren't that bad either.

I hope this had something to do with your question. I understood about 5 words from your post =]

try some Mullard's there about the best i can find that are reasonably priced I use them in my Cary SLP 94 preamp with fantastic results