I have a horn system in my home, efficiency is a bit over 100 dB / watt. There is only one solid state amp. that I have ever heard that I would consider running with it, the Pass Aleph J. Literally, almost indistinguishable from my 300b amps.
I have owned the RWA Signature 30.2 as well. I like the amp alot, the sound is very, very different though. Very full, thick and warm sounding, where as the Aleph J was as delicate and light and pleasant as a 300b amp. If I had less efficient speakers, the RWA would probably be better as it would have a little more grunt, but if you are running comfortably on a few watts, the Aleph J is a winner.
All that being said, if your tube amp is noisy, it is simply a poorly designed tube amp and or some bad tubes. I have a pair of Audio Note Kits Interstage Monoblocks that are completely and utterly silent with my horn setup. I have also auditioned a Yamamoto and Wavac that were completely silent as well. My 2 cents.