5AR4 rectifier tubes - Chinese or Russian?

By the way, Kevin Deal said he'd spend his money on the 12AU7s and 12AX7s and not worry about expensive rectifiers,

Kevin knows what he's talking about and I would pay attention if I were you. Prima Luna are his product line and he knows them as good as anyone. People here probably responded to your query the way they did because of the way you stated your question.

12AX7's - I really liked Tungsrams in another application (a different amp), which can be find re-labled as Amperex. I haven't had much experience with 12AU7's so could not comment.

I would invest in high quality, NOS small signal tubes first as well(like some good Amperex). They(the tubes in the signal path) will always provide the biggest bang for the buck. Still- Why would you want to rob yourself of all that the unit could offer, by not upgrading the power supply as well? Either shop further for the Mullard GZ34s, or pop for the Japanese knock offs, after you experience the signal tube upgrades. Then you can quantify what each step provided in presentation. BTW: Being they are in the power supply, there's no need for the rectifier tubes to be all that closely matched. You just don't want any kind of crazy disparity between them.

As mentioned above, I would go with a NOS Mullard. I did this in my Cary SLP-05 and was blown away by the difference. Worth the money and they will last many many hours.