Turntable in cabinet

For a variety of reasons (kids, cat, spouse) my LP-12 will continue to reside in a built-in cabinet for some time. To make matters worse, the cabinet is near a corner in close proximety to the sub-woofer. I have successfully isolated the TT from the cabinet itself (TT on lightweight shelf on spikes on 1 1/2" plywood shelf on spikes on aluminum angles mounted to sides of cabinet interior).

However, I'd like to dampen any resonances within the cabinet itself if at all possible. Can anyone recommend something that could be applied to the cabinet interior to do so?

Thanks!

Rick