If you want even still sweeter and nicer tone, go to the Telefunken 12AX7, It has absolutely no equal. I cannot speak as to noise level, as every tube must be tested for gain, microphonics and noise. That's what Kevin at Upscale does, but be prepared to pay dearly for Tele's. And yes, I agree that the Tungsram is sweeter than the Sovtek LPS. The only comment I made about the Sovtek is that it is very quiet (the selected ones, like from Aesthetix), and that it was the ONLY tube made by Sovtek that I liked. All the rest are terrible, and I don't make that comment to be mean. There are simply better tubes in every type and model number, than the ones manufactured by Sovtek. In response to your direct question, the volume control is not a good judgement of the signal to noise ratio of the tubes. As you state, there are differences in gain, and even as important, tonal balance. For instance, the Sovtek is fairly bright on the top end, making it easier and more prominent to bear hiss, noise or what ever description you make of it. On the second tube to reduce the noise further? My common sense guess is yes, if you liked the first one, more of the same should make you happier. I still think you should try some very low noise Telefunkens, so you can see what the ultimate is.