Let's start with the best news of all...you can't screw this up! Even if you get a ton of bad advice, misinformation and that sort of thing (what I am likely to say, for example!)...you just can't screw this up. Either way you go you will have wickedly good sound.
Now, the way I understand it, Spectral usually builds out their stereo amp first, then designs/builds the next gen mono's based on that platform. The 250 preceded the 360S2 so is probably going to be closer in character to that later design. Of course there are also benefits to mono's, more power and that sort of things so you gain that with the 360S1, I've owned them and they kill. I guess if it were me I'd buy the later build 250 and put more into cables which probably will matter more than which one of these amps you choose.
Enjoy, it's a real special product.
Now, the way I understand it, Spectral usually builds out their stereo amp first, then designs/builds the next gen mono's based on that platform. The 250 preceded the 360S2 so is probably going to be closer in character to that later design. Of course there are also benefits to mono's, more power and that sort of things so you gain that with the 360S1, I've owned them and they kill. I guess if it were me I'd buy the later build 250 and put more into cables which probably will matter more than which one of these amps you choose.
Enjoy, it's a real special product.