When auditioning speakers for my new system, I found that the Sashas paired with an Audio Research 200 wpc integrated amp sounded great - up until about 80 on the volume control, when the ARC just didn't have the power reserves to handle recordings with substantial bass. So I think your concern about adequate power is legitimate if you plan to play them loud, and that taking your gear to the dealer to see how well it drives the Sashas is an excellent idea.
But although I went with Revel Salon 2s due to my particular room circumstances that required a more forgiving speaker, I will say that the Sashas are outstanding speakers and I think noticeably better than Sophias, especially in a larger room.