Hello,
I'd like to add my 2 cents if I may... the preamplifier of an audio system is what passes ALL the sources on to the power amp. Too often the focus goes heavily in the direction of the power amp, and the preamp choice process is neglected. In the case of Magneplanars, the power amp choice is a more delicate balance than with the majority of other speaker types, but the preamp should be at least of equal quality. I'm not sure what made you decide to use a home theater receiver as the sole "preamp" of your system, but I urge you to explore high quality preamp models to compare with the sound you are hearing as you route your music through the Yamaha. I'm sure what you hear sounds nice enough without having anything else to compare it to, but I've been the owner of several Maggies over the past 30 plus years, and I can assure you that they will reward you for every improvement you make in the chain of components, and source material you use. Btw, I think the 220 is a fine amp to use with those speakers.