sean,your right on track about metal racks resonating, my last rack was a diy made from oak & my new rack is metal & mdf.
my diy rack seemed to absorb or deflect better, i couldnt get my cdp to skip no matter how loud i jammed but the new metal rack threw the cdp all outta whack.
i ended up filling my new metal rack's leg's with spray foam insulation & this has seemed to dampen the vibration's comming up thru the legs & i had to add isolation devices under the cdp.
so far it seems i have corrected the problem but only time will tell the whole story.
mike.
my diy rack seemed to absorb or deflect better, i couldnt get my cdp to skip no matter how loud i jammed but the new metal rack threw the cdp all outta whack.
i ended up filling my new metal rack's leg's with spray foam insulation & this has seemed to dampen the vibration's comming up thru the legs & i had to add isolation devices under the cdp.
so far it seems i have corrected the problem but only time will tell the whole story.
mike.