Someone check my math!
You can use an online calculator to find where your speakers will theoretically top out with spl within the rated output of your amp. Then add 3 db for every doubling of speakers playing simultaneosly.
Ie. 1 speaker 110db
2 speaker 113db
4 speaker 116db
Then you must subtract from this the decible drop from source distance. For this, each distance doubling drops 6db.
So if 1m is 110db
2m is 104db
4m is 98db. Etc.
Axiom specs the m80 in room at 92db@1w/1m. At 4m they should be around 80db.
So take 80@1w
Add 3db for a stereo pair.
All these numbers are purely theoretical. They depend on the listening axis, acoustic damping of the space, and listening material. We are also more sensitive to certain frequencies.
The best way for you to be happy is to listen to your source material in your space and ask how much more power does it really take to get to that next step? Probably lots according to the formulas.
Really, the only way to check this in a meaningful way is to play your reference material and measure peak and average levels with an spl meter. Buying a huge amp will add headroom and can make listening a more engaging and dynamic experience. The purpose is not to increase nominal listening levels, as your amp is likely already capable.
Nominal listening levels are nowhere near the 110db mentioned earlier. That dba is dangerous to hearing at sustained levels.