Guys, you need to get a Soviet 6c4p-ev rectifier in place of Chinese 6z4 (plug'n'play) and try to experiment with 5842 tubes (adapters needed). I did both, and I like the results. But Western Elecric 5842/417a tubes (in my case) are expensive, while other brands are not so much.
Definitely worth the effort. Besides, it's always fun to try different tubes ;)