I just received a pair of the top grade Psvane CV 181T's in the nice pink box from Grant Fidelity. I've been letting them play music now for about 50 hours (I know not the 200+ hours suggested). I'm comparing them to my beloved and well broken in Sylvania 6SN7 WGTA's 1977 vintage.
Right out of the box the 'vanes sounded down right crappy. But after 50 hours, what shines most is their really open and transparent midrange, precise focused images, tight bass, and even frequency response. I can hear waaay back into the recordings with these tubes. They are not as full and round sounding as the Sylvanias and lack warmth in the lower mids and upper bass as compared to the Sylvanias.
The Sylvanias have mids that are warmer, richer, rounder, but not quite as focused and not quite as resolving. Bass is just as deep, but a bit more flabby. Highs are just a bit more rolled off. The Sylvanias sound soooo smooth and warm and more delicate in the all important midrange, something that the Psvanes haven't yet matched.
I'll keep letting them burn in, but I think I've got a pretty good handle on how they sound compared to the Sylvanias.