PM, I'm not familiar with the Yamaha speakers, but I'm quite familiar with your Sony 315 and know that it has plenty of power to drive the M3s to uncomfortably loud levels. The fact that you have to set the volume control higher for the M3s indicates only that they have less sensitivity, which has no connection with quality, size, number of speakers, etc. I have the M22s because I prefer the slightly more forward and clearer mid-range they apparently have as compared to the M3s, but I don't know if that would match your preference. As far as the highs, the M3 and M22 have the same tweeter and are essentially identical there, with quite strong and smooth response. I can only guess that the Yamahas are unrealistically elevated or ragged in the highs if they sound much different. The Axiom highs are accurate. Keep listening to the M3s and don't hesitate to set the volume control higher than you've been used to.
