Weebo,
I honestly don't think you have anything to worry about with the Kenwood in terms of not enough power. Even if Kenwood overstates their power, the VR-507 is a legitimate receiver that should easily power Axiom speakers. If you turn up the volume and it seems to be playing fine with no clipping, then the VR-507 should be fine.
Having said that, with respect to performance, I had been using a Kenwood VR-509 (essentially same as 507) receiver, and there was a pretty big jump in sound quality and performance when I switched to a H/K AVR520. I moved the Kenwood into my bedroom where it is powering Axiom M3's, and it is totally adequate for that purpose. But, the H/K's sound is just much more appealing to me than the Kenwood.
