Hi,
On the face of it, it's not harmful. It's just that you are putting your Axiom speakers into a "sound reinforcement" role that they weren't designed to play. As for the Shure microphone, that's marginal. If you were to roar into the mike doing karaoke, or belt something louder than normal, you might rip out the voice coil in one of the drivers.
Speakers used by touring bands and club owners, as well as those for amplified instruments, are not designed for high fidelity; they are meant to take unending abuse and not have to be repaired or replaced every tour date. It's one of the reasons a lot of club and concert systems sound so lousy but they do stand up to abuse. Years ago, I ran a pickup on a 12-string guitar through a hi-fi amp and damaged one of my speakers. Susequently, I got a dedicated musical instrument amp/speaker and used that for my instruments and mikes.
Regards,
