I am surprised too, regarding the Sasha. What helps the Prelude MTS is that it has many drivers from the floor to a height well above you when you sit down. The music would then engulf you naturally, as opposed have the speakers compensate to image that much sound toward you. Secondly each musical/voice note cannot be described by just one sound frequency. It's a distribution of the dominant and transient frequencies. I think having multiple drivers, if done right, can present the fabric of sound better. The end effect is that the MTS begins to take on some of the body/depth of sound that the Wilson Maxx is known for. It certainly isn't the Maxx. But it is somewhat better than the Sasha, though not quite half way toward the Maxx. Secondly the larger body of sound provides less "distortion" from true sound, thus the sound stage opens up wider.
When doing the audition, I obviously compared apples to orange, between studios and my own equipment. The one that particularly showed me the Sasha was a dump, with one speaker next to the other, and stereo components close by the speakers that would vibrate the day light out of these components. I would also expect that sound reflection and scattering be a concern given that many speakers together. Yet when the studio person claimed that the showroom was set up by Wilson Audio, I don't have a mean to argue. Secondly although studio components are about top of the line in their respective brand, I personally don't think they have the better to best piece for that particular genre of component (i.e. you mostly don't use the same brand for CD player and preamp and/or amplifiers). Basically I am using my own equipment to evaluate the Prelude MTS against their equipment driving the Sasha.