Nice speakers! Very efficient as well. The difference between the M3 and the KW500 is more than just power. With the Hales speakers, the M3 would be powerful enough. Plus, the sound of the M3 is better (clarity and transparancy) than the KW500 and the KW550. The KW500 is brute, and it is tempting to want that power. I was about to purchase the KW550 and was fortunate enough to talk to Musical Fidelitys ex service manager, who has a pristine reputation. He immediately told me to grab the M3. Much better sound quality, he said. I am glad I did. I tried ML and Krell, they were good, but not as good as the M3...Just my humble opinion.