Assuming the dimmers are already there before the "lot of recent changes in the system", how can it be a dimmer problem ?
Check up what other changes you've done with your gears. One hint:
make sure there is only ONE three-wire power cord used for one component only & ALL the other component hooked up together in the same rig only use two-wire power cords.
I have a dimmer control for my side lamp in my audio den since day one, & I don't get any problem of buzzzz or humming at all.
c-J