Tube info

I really like the Brimar CV4003/12AU7 tubes that I got from upscale audio for use in my preamp.

I’ve had great success with CBS 5814a tubes, and Amperex 7316 tubes, in that order, in my preamp. The Brimar mentioned above is good too, but I like the other two better. 

The question is what type of sonics are you looking for from your amp?

I was very pleased with the Brimar CV4003/12AU7 from Upscale... provided warmth with extension. When I changed my power tubes, I went with NOS Tung Sol 12AU7’s which provided transparency and realism. Fantastic tubes and affordable.
Have also tried RCA 5814, but they were better suited for an input gain stage due to their wonderful timbre.

Here is another link with some great info on the different 12au7 tube types and manufacturers, and on how each brand sounds.
http://www.audiotubes.com/12au7.htm

Japanese NOS like NEC are very good.....basically no noise that i can discern, and cheap.  Of course NOS RCA 5814A as well.