Focal Aria 948

I currently have them running on my Antique Sound Lab Monoblocks Better than the SX 1250.  But still not the bass I would like.

Selecting an amp for those speakers if a deeper and tighter low end is what you seek is like chasing your tail. I had the Sopra II for a short while and paired them with Mac, Pass, and Coda and could not wring decent bass out of them despite a lot of positioning. At close to that price point, might I suggest the Dynaudio Contour 60...great mids and far deeper bass.

I use the Aria 948s with a Pass Labs Int 250 and Enleum 23R.  Plenty of bass. Speaker set up is key.  My room is 13’ wide x17’ deep and the speakers are 3’ off the front wall and 2.5’ off the side walls.  Play with toe in as others have said. 

Moved them around a little tonight.  1' from back wall, 30 inches from sidewall. Toe in slightly.  Sitting 12' back in a 12' by 18' room.  Better with this.  More tweaking maybe?

For a fun read by Henry Kloss on Hoffman's Iron Law, I recommend this article from Audio magazine, March 1971:

https://klhaudio.com/wp-content/uploads/2021/05/loudspeaker-design-hofmans-iron-law-by-henry-kloss.pdf