I just spent a couple/few hours on playing around with different preamp tubes in a couple of my amps. The ones I liked the best were JAN 12AX7's, JAN 5751's, and it turned out I had 3 Mullard 12AX7's I didn't even know I had. One was microphonic.
the other two got put to use.
The Sovtek 12AX7 and 12AX7WXT+, EH 12AX7, JJ 12AX7, GrooveTubes 12AX7's, and "China" 12AX7's were never the best sounding tube, in the two amps I was setting up. Regardless of sonics, which is what I was listening for, I also tend to believe the hype that the old US and especially UK-made tubes last significantly longer than new-production tubes.
How much gain does a 12AY7 even have? I've heard of using 12AU7's or 12AT7's instead of 12AX7's, but can't recall ever hearing about someone using 12AY7's... Where are you expecting to use it? For the first gain stage, or the PI?
"The bastards have landed"
www.myspace.com/thechromerobes - now has a couple songs from the new album