I need a quiet tube amp

The Quicksilver Horn Monos are indeed quiet, but see if you can try them out first. I found them to be less musical than their other offerings. I've owned the Mini Monos, and heard the Mid Monos with 90db speakers, and they made no noise.

I am using an Audion Silver Night MKII 7W SET with 104db Klipsch La Scala's, and I cannot hear a sound, even with my ear next to the speaker. I had another pair of SET amps that were wonderful when the music was playing, but could hear the hum during the quiet passages.

Another fantastic amp is the Audiomat Arpege. Very engaging for all types of music.

All the best,
Howard

Tomyran,
You have probably explored this option, but on my Wright Mono 10's I used a 3-into-2 prong adapter, and the hum disappeared almost entirely. With his 3.5 SET amp monoblocks, I found that the hum through the speakers had mostly to do with the quality of the 2A3 tube I was using. When I found an excellent NOS tube, the hum was reduced dramatically.

If those suggestions--and the ground loop check--don't work, I would take the amps to a tech and have them checked out. If there is no issue with the amps, it may be a problem worsened by the 2A3's being used.

Hope my amateur advice helps.

All the best,
Howard