Not sure about actual numbers but I have a test CD that runs tones down to 15 Hz and the M200's will vibrate things at that frequency (Its actually kind of fun to trip people out with this, they don't understand why the can feel it but not hear anything). As far as hum is concerned, I have 10 of the M200's on two seperate circuits and they are totally quiet. Initially they would hum (which drove me crazy) but I was able to trace the problem back to my satellite dish not being grounded to the same spot as the rest of the electrical system. Move the ground and no more hum, ever.