Phono preamp tube rolling.

surfmuz, What I meant is that there are nefarious persons who change the markings on tubes that otherwise look very much alike, so as to make inexpensive versions look just like rare and more valuable NOS tubes.  So, before shelling out big bucks for a Telefunken or Amperex or etc, it is wise to equip yourself with the expertise necessary to tell them apart regardless of the labeling on the tube.  On the other hand, I would totally trust Upscale Audio, Jim McShane, RAM, and certainly others with whom I am not directly familiar.  I would NOT buy expensive tubes off eBay.  Also, there are current manufacture tubes that do sound excellent and are reliable, made by JJ  and Sovtek, for two examples.  There you have good quality at reasonable cost.  In my experience also, some of the Chinese made tubes sound great but have a shorter than average lifespan, way too short.

Tube Rolling is a great experience.
Learning how certain Brands and Production Era's interface in a circuit and deliver into the Downstream of the System is a something that is worthwhile undertaking.

Trusting the Supplied Tubes is the issue.
I have come to terms with the fact that Tubes will make music happen, and to the inexperienced such as myself, I would not know whether one is of the ideal measurement.
An asking price from a Vendor can suggest it is Factory Spec and certain supplied measurements will suggest the Tube is Factory Spec.
Give such a Tube to a Time Served Valve Individual with Testing Kit  and a full knowledge of testing and the supplied Tube can be proven to fall short of the Factory Spec by quite a margin.

I only purchase Tubes today that come with the right to return if a secondary measuring  at my end does not match the vendors advertisement.

I have returned Tubes for the above reason, both  NOS and New.   

As a result of being vigilant with a purchase, I have Vintage Tubes in a DAC, Phon, and Power Amp.
I have selected these over New Tubes as a result of Tube Rolling experiences. 

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.