If the noise increases with the volume control, then that at least rules out the preamp's buffer output stage, and your amp.
In a review of the ET3-SE, it's mentioned that this unit uses a single 6922 tube for voltage gain. They didn't mention whether that tube comes before or after the volume control. If before - then it would be a prime suspect as the noise contributor. You could buy a guaranteed "low noise" 6922 tube from a trusted tube vendor, and see if that helps. If your source is an MC phono stage, then that could also be the (likely) cause of noise.
If all gear is in spec and the tube in question is not a noisy specimen, then it may just be that you've got an exceptionally high sensitivity amp & speakers - which would imply that you'd have to listen with the volume control quite low (i.e. you're throwing away gobs of gain - a prime candidate for a passive, though I still love the sound a good tube preamp even with some excess gain and noise floor).
BTW, being a vinyl and tube 'phile - I don't find a modest noise floor of the white noise variety (i.e. NOT ground loop hum) to be of detriment to the music.
In a review of the ET3-SE, it's mentioned that this unit uses a single 6922 tube for voltage gain. They didn't mention whether that tube comes before or after the volume control. If before - then it would be a prime suspect as the noise contributor. You could buy a guaranteed "low noise" 6922 tube from a trusted tube vendor, and see if that helps. If your source is an MC phono stage, then that could also be the (likely) cause of noise.
If all gear is in spec and the tube in question is not a noisy specimen, then it may just be that you've got an exceptionally high sensitivity amp & speakers - which would imply that you'd have to listen with the volume control quite low (i.e. you're throwing away gobs of gain - a prime candidate for a passive, though I still love the sound a good tube preamp even with some excess gain and noise floor).
BTW, being a vinyl and tube 'phile - I don't find a modest noise floor of the white noise variety (i.e. NOT ground loop hum) to be of detriment to the music.