12ax7 vs 5751


hi all,
i need some advice. i`m very new to tube amplifiers and i`ve been doing some tube rolling.

i currently have a pair of grant fidelity matched psvane 12ax7t`s in my amp which sound fantastic.

what i`d like to know is which are the better tubes, 12ax7`s or 5751 tubes. i`ve been looking at forums and there are folk out there that say 5751 tubes are better than 12ax7 tubes.

can i have your thoughts on this please and also which are the good 5751`s to go for.

i really like the psvanes but if they can be bettered i`d go for it as my next line up of replacement tubes.

my amp is a yaqin mc100b. the tubes i have installed at the moment are.....
2 x psvane 12ax7t`s
2 x brimar 6sn7gty/cv1988`s
2 x sylvania 6sn7gtb`s
4 x electro harmonix kt88eh`s

many thanks in advance guys.
grayf
hiya mac i`m really not sure. at a guess i`d say mullards. the reason i say that is because i read somewhere that these golden dragons are based on the mullards, but i don`t have any experience with mullard tubes although they are on the list of "to get" tubes. i`ve been looking into mullard tubes with the blackburn codes on them. they`re supposed to be the ones to go for. mullards are supposed to have a beautiful warmth allied to great detail. these golden dragons sound like nothing i`ve heard before!
I am gonna try the Amperex bugle boy 12at7 in place of the Golden Dragon 12at7's that came in my pre.
Any thoughts or experience with these?
No experience with those tubes, but I just put Amperex NOS Bugle Boys12AU7s in my Primaluna Dialogue1 and Wow! Wow! Wow! Just like the old song, "What a Difference a Day Makes," what a difference a tube makes! Huge well- layered sound stage. Tone, timbre, airy, clear, detailed yet sweet, fuller with more weight, I'm really enjoying the overall musicality of these tubes. Now, I must find another pair of these for backup. These replaced RCA Clear Top Side getter which were very good. Also put in Yugoslavian Telefunken 12AX7s, slightly bettered the the Canadian NOS Telefunken 12AX7s rebranded Northern Electric that they replaced.
Mikirob
Sounds good. Hope I have similar results with the 12at7's. After that I am gonna replace the tung-sol 12ax7 with the GE triple mica black plates.
Mikirob,
Amperex made a 12AU7 variant in the early sixties called 7316. When I tell you they do what the other Amperex do only a lot better, believe me. The problem is that a lot of people other than myself really like them and the price is quite high. As if the regular Amperex 12AU7s didn't cost enough already.
@ Grayf and Mcpherson. Shuguang made a 12AX7 a couple of years ago that I actually liked. It was called the 12AX7 C9 or 9th edition it was clean and accurate with a good strong signal, not warm but really very good. Then they stopped making them for some reason and now you can only seem to get the 12AX7 B8. I never understood what happened, but if you can find them (C9s) buy them you'll prolly like them.