I have a pair of 40s and have used an Edge M6 (120 watts/ch) and currently a Nuforce Reference 9 V3 SE mono amps (175 watts/ch). Both amps drove the 40s well. I would sell the Edge M6 high current amp if you have any interest. It was $3000 new--sell for under $1000. It is in good shape, say 7 0r 8 on the Audiogon scale.