12BZ7/12AX7 vs. 5751

Why in the Sam Hell would you be rude enough to suggest new speakers? Grimace never mentioned speakers just a simple question about tubes.

Grimace sorry I can't answer your question but I do know 5751's are a replacement for 12AX7. I would contact Cary and Google search. I saw some very good advice awhile back on interchanging tubes but I do not remember where. Sorry.

While I have never used a 12Bz7.I have tried NOS low noise, matched,(read expensive) 5751 tubes in place of the 12Ax7 that were stock in my Tron preamp.After about one month of listening I placed the 12Ax7 back in the Tron.
My conclusion was that the 12Ax7 gave more body to the music,with better dynamics,separation of musicians and wider stage.Others may say that my conclusion is wrong Joe's Lore) but this is what I heard in my room with my components.YMMV

Sam, thank you for the backup. Clearly one of those salesmen who wonders why he never sells anything.

I went to my favorite secret old TV store with thousands of tubes lying around looking for a pair of 5751s, but he didn't have two. However, he did have an NOS pair of GE 6BQ5s which - probably because they're fresh - are a bit of an improvement over the old Mullard EL84s. So... you never know what you're going to find.

I just don't get the whole tube rolling deal.

"I just don't get the whole tube rolling deal."

I must respect your opinion since you are a dealer, with lots of experience I presume. I will put aside some thoughts I might have, being on the other side of the coin.

But I would like to understand your recommendation since you went directly to the speakers. Why not the source, the amp, cable changes, room or power source treatment ? Can you explain why go immediately for an expensive solution ?