Phono preamp tube rolling.

Lewm  I should  proof read more.  Grammar  has never interested me but you got the drift.   I have done lots of  tube  rolling and  changing of tubes in the years.  Your system is revealing  enough  that if you rolled you could hear the difference.   Noticed  I said difference  not upgrade , better a cross the board etc.etc. etc...  

My latest  diy  phono pre I tried 20 to 30 different  tubes in number 1 position.  Wide range of sound difference.   12ax7 is normally at the bottom of list.  So I am not much help to the OP.  In regards to noise 12ax7 is normally one of the best but then comes the sound  well  you can  not  always have everything. 

Was reading the Rouge  manual  and it said if  you want to use  12at7 you can and get less gain.  This would be the first  thing  I would try.  Just  get a cheap pair and see if he likes the sound.  Of course if gain is a issue  it may be better with the 12ax7. 

The one thing I did notice is that mullards tend to be full body and in the right circuit quite musical.  The OP is at least willing to trust his own hears  so  he can roll  and get what he wants out of the equipment  he has.

Enjoy the ride
Tom

lewm, I know that tricks with re stamped tubes… they use acetone to tear off original stamps and than put on a new signs. About five years ago I bought NOS rectifier MULLARD GZ34 from eBay faked like that :) fake signs just smeared off right away right in my hands after opening. So, no eBay that for sure…
I do trust Upscale Audio and TubeDeapot….
regarding Chinese tubes, I had pretty good results with Sophia Electric Blue Glass 6SN7 using them with my preamp…never tried others.  

tomwh, I tried to replace 12AU7 with 12AX7 ones, and it gave me a little bit more gain, not significantly, but noise increased too.. so SQ didn’t benefit from that switch. 

When I first got Super low noise 6922's from RAM Labs I was flabbergasted at how much quieter they were than the stock tubes. This is an ARC phono stage! Every set that I have gotten have been just as quiet. They are so quiet that with the volume cranked to the max I have to put my head up against the speaker to hear anything.

surfmuz, it is always best to use the specified tube.

I’ve done a ton of tube Rolling over the years on the Ares Magnum. The 12ax7 slots make a huge difference. My 3 favorites, from most favorite to less favorite:
1. Mazda silver plates - These have a little extra energy on top, so maybe not the best fit for systems already leaning bright, but they far exceed the next 2 choices in all other respects. Almost as good as a component upgrade. 2. Telefunken - Ribbed plates if you want a little extra zing up top, smooth plates if you want warmer or smoother. Smooth plates are more neutral overall, ribbed can be a little more exciting. Both great tubes, and plentiful if willing to buy used, so don’t overpay for supposed NOS from a dealer.
3. RCA tall black plates. Good overall tube, close to neutral with a touch of warmth and sweetness.

The 12au7 slots, eh I never liked 12au7. You can sub 12ay7 or 12at7 in here. I’ve also subbed 12bh7, which is what I ended up suing the most - MUCH better sounding than typical 12au7’s. The best 12bh7 are 1950s Sylvania black oval plates with D or square getters. RCA of any kind are also good (warm) and Tung-Sol are decent (leaning a bit bright). The real problem with 12bh7 is their noise and microphonics in this application. But the Ares isn’t really the quietest phono stage anyways, so I just went through a bunch until I found a pair "quiet enough" and went with that. For a strict 12au7 sub, the GE 5814 gray plate triple mica were decent enough sounding (warm), easy to find quiet ones of, and affordable.

Rogue OK’d the 12bh7 sub for me, several years ago. These tubes draw 0.3mA more current on their heaters. I’m not sure if Rogue would say they OK it today (they seem to be getting more conservative in their recommendations over time), but I never had any problems.

In all 12ax7-based tube phono stages I’ve had (Hagerman Trumpet, VAC, Herron), those lead 12ax7 make a huge sonic difference. The follower tubes also make a notable difference, though not as much as the 12ax7 until you start trying type substitutes (e.g. 12au7 to 12bh7 / 12ay7 / 12at7) - then the difference can get almost as big.