I thought Craig was providing new production TS 5AR4? Oh well. The major difference in sound with the rectifier swaps is likely to do with voltage drop (more drop = warmer, muddier, softer sound at worst, or romantic, luxuriousness, gloriousness at best). It sounds like the Chinese 5AR4 might be slightly uneven on the two sides. I know this was the case with one of the new production Sovteks we tried. It's just the nature of cheap (or even expensive) new production tubes and hard to make any strong assertion on brands without a lot of samples, and not just that, samples over time, which nobody in the world has time to test. I'd trust the old vintage stuff more because tubes those days were built for critical applications like military radar or IR trackers - this assuming the old vintage stuff hasn't been run into shit - which from eBay you never know despite "tests". The 5R4 I believe has more voltage drop than the 5AR4 / GZ34. Also, give the 5AR4 a TON of time to warm up. Spec is like 15 or 30 seconds, which with sharp audiophile ears means give that rectifier 30 minutes.