Vandersteen 2CE sig - How Loud Can You Go???

A friend of mine is thinking of purchasing a pair of these speakers used. In my opinion, they are a great buy (if set up properly) and also fairly kid-proof (a consideration here). I've had them before, and recall the manual warning about extended periods of high volume. I never really had a problem with this. In your experience(s), do these speakers have a particular susceptability to being played at high volume, or can they rock? Does anyone take precautions with high volume? (When I had a party, I hooked up two sets of speakers to "spare" the Vandy's!).

Thanks, Peter

PS: Amps under consideration include: Stratos with cap upgrade, BEL, Classe CAP-101 integrated, and maybe a modified ST-70. Any thoughts?