Most tubes have some noise, some less than others...unless it's humming or buzzing, and does not interfere with the music being played, I'd not worry too much about it.
Tube noise when gain is increased, tube issue?
Adjusting gain on my preamp improves the sound vibrancy who makes it sound better. But when I turn it higher the tubes tend to make a buzzing/humming noise which goes away when I turn it back.
Is this a tube problem or a gain problem. It's nice to maximize the gain setting before distortion occurs.