I am matching STA-9 & DAC-9 with my Focal Aria 926 floor-stand.
The STA-9 certainly has enough power to drive them, and I believe STA-9 should have enough power to drive most speakers on the market. And for your comparison, the only AMP I have matched with my Focal was a 40w Teac class AB amp, and it didn't go well. I had to sell my Teac immediately.
Regarding the sound, it is a pair of musical speaker. The Focal is known to be on the "bright" side, but I don't feel it with STA-9, so it is good. However, the bass very gentle on Focal 926, (which I like) if you expect more bass you should try other speakers.
I have heard the KEF R500, ELAC FS-247, they all have stronger bass.
In summary, I am satisfied with my STA-9. I absolutely love the size and the build of it. It is the best component I can get with my budget at that time.