Vandersteen

Very very unusual situation .......

What is the rest of your system? Sounds like the new VANDY speakers are an extremely poor mismatch with the rest of your particular gear.
system synergy matters --big time -- and one size does not fit all.

When you say they " fall to pieces..." , can you elaborate please? 

What speakers were you using previously in this same system where this did not occur, and what equipment are you currently using?

I am not understand what falls to pieces means.  Symphonic works could be the way your source and preamp send the signal, same for rock.