Does the BeoLab 2 cause any problems when on the cabinet?
What you could always do if you come across problems, is ask your dealer if he or she can supply you with some of the black rubber cable tidy 'snake' you see coming out the back of BeoLab 8000s, and run that around the inside rim on the base of the BeoLab 9s.
Ultimately, if your BeoLab 2 sounds fine, then I'd imagine the BeoLab 9s will as well.