I used a can of compressed air (with thin tube attachment) and sprayed air at the joint between the terminals and the amp wall to test for air leaks. Air was leaking through.

For this reason, I applied a second, thin layer of silicone caulking around the perimeter of the terminals and smoothed it very gently with a finger. That seemed to stop most of the air leaks.

Keep in mind the terminals are an open design, so a small amount of air will go right through them where the push buttons are. I am deciding whether to use some kind of temporary putty, like Blu-Tac on the rear to seal up any remaining air leaks.