5AR4 rectifier tubes - Chinese or Russian?

Your rectifier tube will have a marked effect on the overall sound of your unit. By going cheap there, you'll be ripping yourself off for a lot of music. If you went with a pair of NOS Mullards (GZ34/CV1377, from the Blackburn plant), they'd probably outlive your ownership of the unit, and would definitely improve the unit's presentation(compared to ANY new production tube).

If the Mullards are beyond what you'd like to spend, you might look into those Japanese Mullard copies. I've no personal experience with them, but if Kevin gives them his endorsement- that speaks volumes.(http://www.upscaleaudio.com/Japanese-5AR4_p_75.html) I DO know that the Japanese are positively anal when it comes to quality control and consistancy in manufacturing practices(diametrically opposed to the chinese mindset). You might contact him, and ask his opinion with regard to their use in your unit. He's always happy to assist a fellow music lover and tubeophile. It's a shame he doesn't have any Mullard GZ34's(which would still be my #1 recommendation).

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.