Go with the M750 amp. It is a better match for the 3.7i's. Impedance drops down to 2 ohms and the 750 will do it. Maggies need high current, high capacitance and high watts to sound their best. I would double check with Frank if the 750 is compatible with a 2 ohm load. If not, consider the SET 500 which is a wonderful sounding amp and stable down to 2 ohms.