12au7 tube?

Mullard EL34’s are great and there is opinions about the differences in sound between the single and dual getters. I think I have both but never compared to hear which is better. I did evaluate between single getter 1960’s Mullard and 1970’s brown base Tesla dual getters. The amp I used to compare these tubes was a Conrad Johnson MV55, with 1945 Sylvania 6SN7W short bottle driver tubes and 1950’s Mullard MCI long plate 12ax7’s driver tubes. The Mullard is just a great all around tube. Very well balanced with Great detail, smoothness and musicality. I found the Tesla, in my amplifier tested, to be more euphoric and engaging. The Tesla had something special that fleshed out the information above the Mullards. Strange thing, even though I feel I was getting a more fleshed out midrange and more immediacy from the Tesla’s, they also had this sense of warmth to them. When I heard the Mullards, no warmth, just musical and straight up good tube. When I play the Teslas, warmth and euphoria and midrange clarity returns. 

Mullard MCI 12ax7 input tubes. 

Do you ever somehow try to musically match 12AU7 driver and power output tubes in advance or it is just a matter of experimentation? I mean, if I am lucky at some point and get a set of EL34 Mullards should I also consider replacing 12AU7 RCA blackplates driver tubes with Mullards ?

No I do not ever try to match brands of tubes together nor have I ever thought about that neither do I see any benefit to it. Almost all of my equipment is operating with all different brands of tubes. Even though I had Mullard MCI 12ax7’s as input tubes, my favorite 12ax7 is the Amperex long plate double DD getter. But at the time of evaluating the EL34’s, I had the Mullards in the input. The Mullard MCI btw are some of the best 12ax7’s ever made.  In the beginning, Depending on the type of tube equipment I’d own in the past, I usually was very curious at how much improvement in sound I could get by picking up premium tubes that were favorites by many audiophiles that were in the hobby before me. Slowly I began purchasing tubes and listening to them in my amplifiers to hear what they sounded like and to satisfy my curiosity. Nowadays when I’m in need of a specific or special sound I’m hoping to achieve, I have some of my favorite tubes to put in place and see if it helps. Ive been in this hobby for 30 plus years and I already know by listening to a system if it’s good or if it’s lacking. I only swap tubes today if I hear a problem. If it sounds good, I change nothing. My ears tell me when something is transparent, revealing, airy, engaging, natural, and all the beautiful things we want to hear from our systems. If I purchase a new piece of equipment that has Chinese tubes, I very much might keep those tubes in as long as it sounds transparent and good. When I purchased my Conrad Johnson Premier Four, it arrived with 8 Shuguang Chinese EL34’s. First thing I wanted to do was get them out and put something better. But after playing the amp for the first week, I found no issue with the Chinese tubes. To my ears, they sounded great and were doing the trick. So instead of putting in 8 Teslas, I searched for more Shuguang tubes and purchased 16 as backups because in the end, it just sounded fine. I did change out the input and driver tubes on the amp to something better from my vintage stash. I feel setting up a system is a mix of a lot of different stuff. I don’t recommend using the same brand of tubes the same way I wouldn’t recommend using the same brand of cables throughout a system. Building a really nice sounding system is something that is done one step at a time and to get it to be really, really good, it usually takes time tweaking and making little but worthwhile adjustments. It can take yrs till it all finally comes together and the funny thing about this hobby is that when that happens, usually audiophiles still aren’t happy.  I do t think many audiophiles will ever be content or happy with their systems. 

Well, most audiophiles are hard to please and always strive for even better sound than they might already have.

I see, no real reason to think that one tube brand everywhere would have an advantage.

With cables, I think it might depend, though I don't have enough experience to be sure.