Like in my other comment, my Cornwall IVs are mostly silent, except for probably the Jolida’s volume at around the 60% mark and anything up and down from it the sound is gone, and the Decware SE84C-S is the noisiest by far but still doesn’t effect when music plays. Decent tube amps will not have much noise if any, and usually if it is, it shows the quality. Don’t go for a cheap one too, like under 500. They don’t really use the tubes to their full potential either, sometimes just as a layer on top or for decoration. Something like the Willsenton R8 would be the best bang for the buck and would last years.

Also as a note: it may be the tubes being microphonic. So any vibrations getting into the tubes may show, and if you tap them while connected, and they make a sound, it’s microphonic. Some may be able to handle that, some won’t. You’re right where the higher the sensitivty, the more likely to hear noise, but at the same time, the ones you listed are less likely to have noise because the have more watts. Remember, for example, the Cornwall IVs are 102db sensitive. Some say it is inflated, but still. The Decware only has 5 watts per channel, the Primaluna has 40 watts. The first watt is what you’d only likely use, but the Primaluna probably doesn’t run them as hot as a flea-size watt amp. I’m not an expert, but it only makes sense because even if you only need 1 or 2 watts, out of 5 is a lot more of it than 40. In Solid State, it can be the opposite because it may hold lots of power, but not quality power but I’ve never experienced that. I may get ahold of Magnepan 1.7i’s and will have to get a higher powered amp and experiment with that on the Cornwalls