Many thanks for these impressions and good wishes, newzooreview. The texture, timbre, and spatial cues are precisely what attract me (in principle and by reputation) to the SA products, so I'd just need confirmation on those points. The three areas I particularly want to audition involve the tonal character/voicing of the AMT tweeter, the subjective depth of usable bass, and the differences in the "on-axis" and "outside the sweet spot" balance (between the M and X series, and from what I'm accustomed to with my von Schweikerts0. I don't expect them to be similar, but I want to be sure that I'm comfortable with how they'll work in my house, and which tradeoffs appeal most.
For instance, the rated low-end extension on the X4 is 32Hz according to the web site. I expect that Mr. Shaw is conservative, and I presume that rating is the -3 dB point. I expect the bass to be fast, tight, and tuneful. Is there usable bass down into the high/mid 20s or does it drop off sharply? I would want to be comfortable that the opening to the Mahler 5 or the last movement of the Saint-Saëns 3rd etc. have the appropriate perceived weight. Though I listen to all kinds of music, I don't need club-level electronica bass impact, but my von Schweikerts play cleanly down to 20Hz so I would want to evaluate the bass quality vs. extension tradeoff carefully. I probably listen to more baroque orchestral, all-era chamber music, and jazz than big Romantic orchestral, so I'm not fixated on one aspect, but I don't want to live to regret a limitation.
All else being good, I prefer passive rather than active for several reasons, some simply to do with power management in my listening room, which is my living room.
And I very much want to hear the Beyma AMTs as spec'd for SA. I have high expectations, but again want to make an informed evaluation for my space (very unusual shape) and listening scenarios.
Thanks again!