Im using the same tubes John. Baldwin labeled Sylvania Chrome Tops (black plates). Got them off ebay for 20 bucks and shipping if I recall. They were also NOS. I also have a Sylvania labeled used pair and a NOS pair of Silvertone labeled sylvanias (same plates, flashing doesnt extend as far down the tube). I agree, they are "rounder" sounding than the 12AU7's based on my experience with both tubes in Crack. I think most of the 12AU7's I tried are more treble forward. Some being too treble forward/bright for my tastes but the good ones being a bit more detailed, so I would agree with you there. But I really liked the 6SN7s and preferred them over the 12AU7's overall, so I built the FPIII with them from the start ... I was using a 6SN7 with adapter in Crack.
I figured I would go end up going back to a 12AU7 in Crack but seem to be leaning toward a 12BH7 instead, atleast for the time being. That may change.
I have a couple of VT-231's as well. I know one of them is good as I rolled it into Crack. I havent tried the second yet. I'll need to check it and then drop them into FPIII and listen after a little while. But I didnt think the regular Chrome Top Sylvanias gave up much to the VT-231. They seem to be a bang for the buck 6SN7 (relative to the $'s that the consensus top 5 6SN7's tend to go for). I've been saving the VT-231's for a try in FPIII but wanted to get good and familiar with the FPIII with the Chrome Tops before hand. I have some other 6SN7's as well but prefer the Sylvanias so far. But the GE's arent bad at all either, but an even "rounder" sounding tube.
