will they go louder

Sounds like you might own the wrong speakers for your son to enjoy. Magnepans look like they should play at ear bleeding levels, but my experience is they wont in large rooms, or if you sit past 8ft from them. For reference I am speaking 98-100 db's or more.

One thing to make maggies have strong bass is to stick something alongside to block the front/rear bass cancellation. with a board alongside each trim strip on thesides, the bass is VERY much stronger.
On my 3.6s music with bass played at say 75dB, exact same musci, same volume etc, with boards six ft tall and 8 inches wide on only the bass side (not on tweeter edge) increases the SPl at seated position by 4 db.
and that is all bass and lower midrange.
So try adding a board to the sides ofthe panel. I can just place one next to, and tape the top edge with packing tape, and it really ROCKS with the bass.
If you want hard rockin' slam, add a temporary 12 inch wide board (as tall as speakers) off the sides. You will not believe the bass coming off that speaker...

Do you have 1W/1M spec of your speakers? Then calculate the theoretical max SPL of your system at 1 meter with the amps you have (it will be less due to room absorption). Then starting at 1 Meter, calculate -6dB less for each doubling of distance to your listening position; this is the theoretical max SPL of the system at your listening spot.

Maggies are not point source speakers -they are dipoles- so the rules are a bit different. At least this can help you get a rough idea of what's happening.

Can you lower the amp gain controls so your son cannot drive it to full output (the fuse popping point) using preamp gain?
Brad

my 3.6's register up to 100db and they are a great rock speaker, they require great amps and tons of power

No really stay with the recommended fuses. You might just move your listening position closer to the speakers. More volume and cheaper then new speakers.