Herron VTPH-2 12ax7 Recommendations?

My new VTPH-2 is breaking in nicely. Tough to say I've ever heard a better phono pre and I've heard (and owned) a lot of them! I've got the version with 2 12ax7s. Any suggestions from other Herron users for NOS?

Might not be a bad idea to go with the Herron installed tubes for awhile to let it settle in.  Chances are they didn't skimp on the tubes and that they were selected and tested by Herron for electronic characteristics and durability.
Great Choice!  I use Telefunckens in my VTPH-2.

Agree with stevecham, use the stock ones for a while before you start tube rolling.  Keith Herron, when he gave us a demo at an NJAS meeting, felt pretty strongly that there should be no need to change the ones he chose.  If you do decide to try different tubes, I always prefer Telefunkens, but I like their sound and their longevity.  You'll need to ask yourself what about the sound you want to change, then go from there (an excellent source for that kind of information is Andy Bouwman at Vintage Tube Services).
I've spoken with Keith about this several times and he has respectfully and gently discouraged tube rolling. He has a particular sound he is after which is achieved with the stock tubes and he is also very practical in his pursuit of hi fi so does not encourage the use of tubes that may not have the reliability of what he ships with the unit. Besides, the VTPH-2 sounds so darn good why mess?
I agree with stevecham, rcprince and dodgealum. 

I have owned both a VTPH-1mc and a [currently] VTPH-2.  I have never wanted for a different sound.  The original tubes were always very satisfying.  I'd hang with those tubes for a year or two to see how the VTPH-2 sounds to you over the long run.  That said, keep in touch with Keith Herron.  He might just find a tube combination he thinks makes a favorable difference.

Speaking of the Herron phono amp and 12AX7 tubes.....the 5751 tube is said to be a 12AX7 substitute, a military grade tube with slightly lower gain than the 12AX7. Does anyone have experience with the 5751 in a circuit designed for the 12AX7?
When I had my Octave V70SE then later the V110 I had used the RCA triple mica black plate in place of the 12ax7 input with great results. It was a warmer overall sound. Of course I did get the OK from Andreas Hoffman at Octave. He also said for those integrated amps 12au7 could be used in place of the 12at7 driver/splitter tubes which is also a lower gain.

That said I would contact the manufacturer and ask if changes like those will work. Some manufacturers design allow for flexibility while other do not. 
dhcod-Good call on picking the Herron. I've had mine for about 3 years and it has served me well. When I got it, I asked Keith about tube rolling. He felt that he had selected the best available tubes that are in production. When I asked him about vintage tubes he said there were lots of options and wished me luck. I have tried Telefunkens, Bugle Boys, RCAs and GEs. I settled on GE grey plates from the 60s for all tubes but V5. I left V5 stock which I think is EI. Vintage tube aficionados will likely snicker at my GE pick. I like them because to me they sound like 60s US audio which is at the roots of my love for this hobby. YMMV but I agree with others to let the phono stage fully break in before you start rolling.
Thanks everyone! I did speak to Keith and he kinda said what he said to you.... which is why I was asking for suggestions. It seems like at some point towards the end of the year, I might just invest in a pair of smooth plate Teles and give them a listen. Mine is the lower gain unit... two 12ax7s, so it’s less of an investment.

Thanks for all the suggestions.
I feel like I have to say again how truly fantastic the VTPH-2 is. If you are in the market for a phono stage, even if your budget is twice the $3650 it costs, make sure you listen to one!

Also Herron's customer service is second to none. That make a huge difference when you are buying something at this level. 
Mine is around 10 years old and at the time they came factory with Ei- 12AX7.
I love mine the way it came--no desire to change it. And I agree with dhcod about Keith's excellent service.
Buy a pair of good used and matched Telefunkens and compare. If no likey, resell.
I use NOS Sylvania Gold Brand 5751s in place of 12AX7s in my Herron VTPH-2 with no problems at all - to my ears they are a better choice in most circuits than the 12AX7 (smoother, better balanced, slightly warm) and the difference in gain has never mattered to me as I already have more than I need. I have also used NOS Tungsol 5751s in the Herron and found they accentuated the bass in a way I like (both more of it and tighter) but haven't been able to get hold of quiet ones. People will say that this is changing how Keith wanted the unit to sound, but so what if you find you prefer it that way and anyway, it's both fun and informative to experiment, if you can afford it. I bought my Herron secondhand and it came with cheap nasty 12AX7s of some brand I don't remember, hence I experimented. In general, with the exception of the increased Tungsol bass, I have not found a huge difference between various alternatives in this circuit. 
Thanks ochremoon. In the 80's I had the Frank Van Alstine Super Pas in which he used 5751's (Sylvania, if memory serves) instead of 12AX7's, for their linearity and low noise said Frank. I had Keith send my VTPH-1mm with two 12AX7's and two 12AT7's in order to get the lower gain and higher overload margin that combination affords. I use a very high output cartridge (5mv!), so I don't need the gain. I believe I'll audition a pair of 5751's in place of the 12AX7's myself.
Went ahead finally and bought from a well reviewed seller on eBay a matched low noise pair of Telefunken 12ax7 smooth plates. I'm not sure how it's possible to make such a great phono pre better but somehow these tubes do. It's just more of everything that the Herron is so great at: tonality, soundstage, dynamics. I'm sad when the day is over and I can't listen anymore. 
One thing though, the "matched" teles were not so I’ve had to adjust the balance on my VTSP to 1 o’clock. Keith says no sonic penality, but it makes me nervous....
Another update for people searching the archives for tube advice on the VTSP2: Telefunken 12at7 are a HUGE upgrade from the stock EH. 

In the end I’ve found this unit to be very sensitive to matching. Trying to get a solid center balance with NOS requires some swapping of sides with both tube types. Worth it though. Once it’s dialed in, I think it’s as good as anything I’ve heard including my ASR Basis Exclusive. 
One final update. I grew tired of the Telefunken 12AT7. Too analytical and I still wasn't able to match the balance very well with them and I found out why: it's the middle 12AT7, the one supplied as an Ei tube. It's the single output tube and that's the one that was out of balance. I put one of the Telefunkens in there and everything just came together. I started out with generic Holland labeled 12AT7s to replace the Telefunkens and everything was great, way way better than the stock 12AT7s. Spent a bunch of money on Mazdas and frankly the upgrade wasn't worth the money. A bit bigger soundstage than the generics. Maybe a tiny bit smoother vocals. Strings are nicer by a bit. So technically better but I was very happy with the generics too.