I think the improved DETAIL SQ has mostly to do with the overall design. I think the driver types (AMT, Ribbons, Domes, Silk, Al, Mg, Titanium, Be, Diamond) may have a contribution. I used to own Salon2 (Be), 802D2 (Diamond), KEF Reference (Titanium), Phil3 (RAAL), Orion (Al/Mg).
But I also think the significant increased in the surface areas of the tweeters and mid-woofers/mid-range has a significant contribution.
Most speakers have approximately ~ 0.8 Square-Inch of surface area for the tweeter. The SV831R has approximately 6 times that much surface area.
Most speakers have approximately ~ 33 Square-Inch for the mid-range/mid-woofers. The SV831R has almost 5 times that much surface area.