@bigby , I have this itch that tells me the problem is with your preamp. Spectral equipment is designed intentionally very broad band and is notorious for this kind of thing. I have a friend that dumped his Spectral system for McIntosh system. The preamp had a problem so he sent it back and hooked up an older preamp. It burned the Spectral amp right up. Torched! So, he had to send that back and you do not want to know what he paid to have that fixed. McIntosh has a reputation for reliability. So, he was not taking any more chances with newer electronics companies. Mind, the Spectral equipment sounded wonderful.
Do not try to use the Spectral gear with anything else. But, it might be interesting to try another setup, even an integrated. Otherwise set up the Spectral gear someplace on the other side of the house. I'd bet it stops or has a much lower volume.