I heard the new D'Agostino Progression 800w monoblocks last night

Dan and co. never mentioned the topology, but given that they're stable and double power all the way down to a 1-ohm load (6400 W), weigh over 150 lbs. each, have 84 output transistors, and functioned as space heaters in the demo room, I'm inclined to guess Class A.

But it doesn't work that way.  The amp is likely Class A up to some power level and impedance (as are ALL Class AB amps!), but certainly not to full power at 1 ohms -- that would mean it would have to consume and put out heat equal to a theoretical minimum of 12.8kW.  Considerably more in an actual build, and very unlikely to be within the continuous AC power levels supplied to that room.  

Other than with single-ended class A amps (but not including pseudo push-pull types like PASS Aleph), pure class A changes to class AB when the output current goes above what the static bias level supports.  So always take the "Class A" designation with a big grain of salt.

I was also at the same event.  I can't really comment on the impact of the electronic and speaker combinations except to give an overall  impression of the rooms.  I listened to four rooms and my favorite was the room with the Maggie 20.7s.  The second best was the B&W room with the 800 D3's.  The next was the Wilson room and the last was the Focal room.  I think the Focal Sopra room suffered from the room itself.  To me the Wilson room didn't impress me.  The speakers and electronics were new and I felt the speakers were directional and had an etch in the high end.  I have only heard one Wilson system that I liked at a mastering engineers facility.  The Wilsons always have a grit and etch that I can't live with and in this case at $110k.  Just my two cents.

Goose, your impressions track with mine pretty well. I got to three of the four rooms you auditioned--D'Agostino/Wilson, ARC/Magneplanar 20.7, and McIntosh/Focal Sopra No.2.

I was probably making allowances for the D'Agostinos and Wilsons having no break-in, and the bass power was a bit overwhelming, but the room was relatively small. Ditto for the McIntosh/Sopra demo. Too much bass around 40 Hz, which again is probably room overload. 

But the Maggies, oh, the Maggies! As soon as music came out of them my emotional center went "Aaaaaaah!" So musical, so relaxing, so involving, with a very natural and focused soundstage. When I brought my humble 1.7s home two years ago, I noticed two things right away--how quiet Maggies are compared to dynamic box speakers (with few exceptions) and how the out of phase backwave helps cancel the room boom you get with conventional speakers. No bass traps needed.

The next day I played a fair amount of music at home, and even after hearing those great systems at Music Matters, my own Maggies and tube phono and line stages kept me happy and engaged with my system.

I do intend to experiment with placement a bit (mostly widen the distance between them) to get something akin to the soundstage I heard from the 20.7s.

Good to read that you had a fun time. I hope to attend one of these Music Matters events someday.

I have no doubt that the Progression 800W monos were sublime!  D'agostino rules!  
I concur with "goose".  
I continue, over and over (at least six different occasions/systems) to hear that super annoying spike on the top end of Wilson's. I keep thinking it's me, but it happens over and over.