Let's roll: what pre-amp tubes should I consider next?


I am looking for some guidance from experienced vacuum tube amp users. I have a Unison Research S6 (most recent model) which runs six x EL34 power tubes and two x 12AX7 pre-amp tubes.

Having gone NOS in the pre-amp section, I've had great results over the new manufacture Tung Sol 12AX7s that come stock with this integrated. The tubes I've played with are the Philips Miniwatt 12AX7s and the Siemens 12AX7s. I like what both have to offer, but there are differences. The Miniwatts being warmer and contributing to an overall more subtle listening experience whereas the Siemens are more precise, producing a sound that has attack, excitement and thrill in abundance. However, I find the latter can be a bit too much in the upper mid/lower treble region some times. Is there another new manufacture (thinking Psvane?) or NOS (Brimar, Mullard, Mazda) that would give me the best of both worlds? Good tone and timbre while maintaining a sense of involvement through speed and attack?

What are your recommendations?

funcrusha


funcrusha
@mickeyb I'll mention them again. Telefunken ECC83 (smooth plates over ribbed plates) are the best 12AX7 type after the Shuguang I listed above. The Teles are neutral and transparent. The Shuggies have better frequency balance, extended highs, and cleaner, deeper bass.
Another vote for current production Gold Lions. I like the extension they give on both top and bottom. I use them in Bob Carver VTA-120 monoblocks as well in a Manley Chinook phono stage. 
Thanks for all the responses. Lots to think about on the NOS front. I have tried Gold Lions 12ax7s, and they didn't suit my tastes. In my system, they sounded lean and a bit bright up top - though I know they have a reputation for being dead neutral.

Will seek out a pair of Psvane 12ax7s and either Sylvania or Mazda old stock.

funcrusha
I’ve noticed some clear differences between 6SN7GTBs that both my pre and power amp currently use, and NOS GEs are my faves for those. I continue to use 12AX7s in my guitar amps (and previously in my Jolida 502p amp also, although I no longer own that amp). I did wind up using Gold Lion 12AX7s though, as they sound great, are consistent, and are readily available.
For NOS Tubes I love the Mazda's.  Top end sparkle and a very dimensional.  I am running 12AU7s in the input stage in a power amp and love them.

NOS Mullard's are decidedly warm.  Wonderful tubes if you like that sound profile.  Not sure I would pair them with an EL34.

For current manufacturing, I would look at Sophia.  Great sounding tube with no real weaknesses.  

https://artaudio.us/products/sophia-electric-12ax7-tubes-ecc-83

If you are interested in rolling your EL34s the Sophia Coke-Bottle EL34 is freaking amazing.  

https://artaudio.us/products/sophia-electric-el34-st