[prepress]

Originally Posted by jdandy

Charles.......The phono stage, particularly the moving coil phono stage, has such a high amplification factor to get the low millivolt output from the cartridge up to a level the preamp can work with, any noise in that stage will show up and be amplified through the line stage. The line stage tubes are the last stage of amplification for all inputs through the C2300 including both phono stages. The line stage output can tolerate tubes that aren't super quiet because its amplification factor isn't as dramatic as the MC phono stage. I always install the quietest tubes I can get into the moving coil phono stage, both in the C2300 and in the C1000C/T preamp that I owned. It makes a world of difference in signal to noise ratios, especially as the volume is raised.

If you are not using your phono stages (MM or MC) then leaving the marginal Made in China tubes in place doesn't hurt anything because you are only using your line stage tubes. In that case I would still recommend the best tubes you can find. Everything matters.

That's what I suspected and you've confirmed it. With no signal playing, the volume was turned up way past my normal listening volume before I heard any appreciable (to me) noise. Since I never go higher than the low/mid 40s volume-wise, perhaps noise isn't a big issue. But I leave the door open to trying a different tube out of sheer curiosity.