45 watts in 8 ohms, probably around 90 watts at 4 ohms with the Maggies. He wants to get to 90 dB. Panels like the Maggies only lose 3 dB per doubling of distance because they are large arrays, opposite of a point source which decays at 6 db per doubling of distance (most conventional speakers). Lets see here the maggies are around 85 db sensitive right?

1 watt-85db
2-88
4-91
8-94
16-97
32-100
64-103

If he sits 12 feet away, approximately 3 meters, the spl at his seat would be roughly 97 decibels if I didn't screw any of it up. He'll get louder than he wants at 12 feet and only 64 watts. He'll even get louder than he wants at 32 watts. Your amp sounds fine assuming it can handle the 4 ohms.