I replaced the Psvane Classic 2A3-C's that came with my Stereomour II kit with matched NOS 2A3 RCA-construction black-plates (Sylvania branded), which I like a lot. Obtained from the very nice folks at Radio Electric Supply, $150 ea. The Psvane is a nice tube, but the RCA black-plates are definitely a cut above in refinement, most apparent in high-end smoothness without out any compromise in detail. This is in a new modified Stereomour II, (
https://forum.bottlehead.com/index.php?topic=15167.0) that doesn't yet have the shunt regulator or DC filament supply upgrades added. I have very sensitive speakers so I hear significant the AC heater hum, and noted that the Psvains are definitely the noisier tube heater wise, but the RCA's aren't silent either. I have over a hundred hours on both tube types, and noted the Psvanes seemed to benefit much more from burn-in, especially early on, than the RCA's.