I've got an Audio Research Classic 60 driving my Magnepan IIIa's and it is truly an awesome combo with plenty of enough power with its measley 60 watt rating. It plays just as loud as it when I had an 200 watt Aragon push my 'Pans and it just sounds so much better.
A lot of cats will tell you that you need big ss watts to make the 'pans shine. This urban myth is one that must be put to an end. Tubes will do you right. You don't need a 600 watt Carver unit.
Don forget that the 'pans have very flat impedance curve and are 4 ohms throughout. As long as you have a 4 ohm tap and 50+ watts, you're in business. It's not like your trying to drive some Thiels with an impedance curve that resembles Dick Cheney's EKG. Some tube amps will have a problem with speakers that have jiggy impedances, that is what God created solid state for.
I've auditioned the 3.5's with an ARC VT100 and it was indeed a glorious experience.
Of course solid state will work too. If you do go that route, a good tube preamp from ARC with a Bryston amp mihgt just be what the doctor ordered.
Ciao,
Daniel