I listened solution set with a q5, and Constellation. Argo with Rockport, inspiration line with wilson Alexia. IMHO Solutions are darker and more close to ss sound, but in a way different then ss maybe a more ss I had found them cold maybe a lifeless littlebit. Constellation is more close to tube sound in a good way, extra ordinary mid range, very fast and energic, they are very different in sonic presantation. If you are planning to buy pne of it, I highly suggest you to listen both them. I think if you like one of it, wont like other(or prefer in your system) also i think both of them are very revealing components, system match is crucial.
I have a totally opposite view of Altanpsx. I own Solution 7-series pre-power and compared to Constellation setup. Both setups sounds not like ss but a little more tube sound on mid ranges and solution is far better on speed and control. Whereas ? did own Gryphons in the past and they are definitely darker than Soulutions and Constellations, but again you should listen to all 3 of them, Since everyone tastes are different.