I looked at the Magnepan website, and the MMG's are 86db and 4 ohm.
The amp has 4 ohm taps, and its 25w. To get to 98db you would be using 16 watts. Depending on your listening habits, 98db is pretty loud, however it all depends on other factors between the speaker and the amp.
Send an email to Mike Sanders at Quicksilver, he would probably have a more definitive answer.
-Brian