tube suggestions/ brand new to tubes

Congratulations. Tubed preamps are the way into tubes. It's a wonderful world. 

I'd recommend listening for a few weeks. Get to know the sound, inside and out of your preamp. Then do some research... AI will likely outline generally which tubes will sound like what. Then you can proceed in which ever direction you want to go from your starting point. I would imagine over the first few weeks of listening a direction will slowly become obvious... and hence the tube choices. 

I also run an Aric Audio Jackpot.  At this point I’ve rolled 6 different brands of 5751’s but have not tried any 12ax7, 12au7 or 12at7’s yet in the input position.  Aric told me the circuit was designed best for the 5751 but obviously works with the other types.  He also told me generally how different the other tube types sound compared to the 5751’s. I have also rolled 3 different brands of tubes in the buffer position, RCA, Amperex and Mullard.  It was very surprising just how much different buffer tubes changed the sound.  I can give you my thoughts so far on the various 5751’s but you might want to PM me as it is long and a little convoluted as in the middle I had a power condition device go wanky on me and I didn’t know it. My general opinion is the same as Terry London said in his review for favorite combo which is a Mazda in the input socket and an Amperex Bugle Boy in the buffer section. 
 

I’d get at least 50 hours on the preamp and original tubes before changing things out. As previously mentioned Andy at Vintage Tube Services is great. He is slow but if you tell him that you don’t need matched pairs it should speed up the process. I hope that helps. Good luck.  And by the way, it is a friggin awesome preamp!
 

Jeff

Brent Jesse, well respected, just sold his business told me: leave the unit on, no content needed, for 60 hours, tubes break-in done.

After that, listen.

@signaforce , @larryi , @jjss49  

First, I would like everyone for their advice and suggestions. After listening to you all, I realized,  HOW much I don't know!!!!  The best advice from all is to listen for that maybe 100 hours,  to see the flavor that your listening to.

Upon first listening, my SVS SB 3000 was dialed in perfectly, and the sound from the Guarneri's was just right. SVS set at -10db (if that's is saying it correctly) had to really push the sub in the system to get the right BASS. 

As soon as I hooked up the Jackpot, with the same sub setting, it was really terrible, BASS HEAVY,  CRAZY. WOW, was I shocked, and not in a good way. I laughed and said to my wife, What did I do? She said calm down and adjust you SUB. I almost spilled my Buffalo Trace, which really would have been  tragic. Taking the wife's advice, I had to go all the way to -20db for the sub to be dialed in, I was amazed. However, after listening to Audirvana 24/192 Stairway to Heaven, and Metallica, Nothing Else Matters, I was PLEASANTLY surprised. The bass was far more detailed, and deep,and accurate,  the clarity of the Mid Range, voices, instruments was very evident. My impression changed immediately.  

After reading signaforce, larri, and jjss49's post., I am really focused on more detailed and dynamic presentation, as you all said my system is generally considered warm.  I will listen for a few hours this afternoon, if time permits. It seems from what I'm able to discern,  I would prefer that more detailed, dynamic sound,  which from what I can gather would push me toward Telefunken or Maybe Amperex (Bugle boy was suggested). I'm going to start looking later this week for a tube or 2 as a back up, should something happen prematurely to my supplied Tung-sol 5751.( input stage)  If any of you have one that you think would fit my musical tastes, please let me know about purchase. Thanks all so much! Robert TN

I will repeat what others have said.  You need at least 50 hours on the tubes and lots of listening times.  I like to listen during breakin at least periodically for the changes. Tubes are a bit like gardening.  It is a slow process to see or hear change.  

I recommend new tubes.  They are making news tubes specifically for audio and honestly, I think they are better than playing the made 50 years ago NOS game.  IMO, new audio tubes made with modern design tools and equipment are more accurate than a tube made 50 years ago for a radar or basic radio.  Tubes already add in tube flavor and many NOS go too far into tube land.  Now if you need or want that go for it, but I prefer the accuracy of new tubes.  For small signal tubes, I have found Rays Reserve and Gold Lion Gold Pin to be the best in the 12AU7 tubes.  Great clarity and still the holographic sound of tubes.  I find 40 to 50 hours is needed to for break in for my ears on my equipment - might get better beyond that, but if so, it would be small and I am on to different upgrades.  Finally, my tube preamp did not like being paired with the Gaia isolation feet - the sound was flat and without sparkle and I lost soundstage.