OK, so you dont see any problem with the VP-100 and the QS4s? I will be sitting very close to the QS4s so loudness should not be a problem, but my experience with center speaker is very limited.
Also, for music, I like mostly rock (like Led Zepplin). A am a musician myself (bass player) so I do understand the necessity of a good sub! Although, I'm looking more for quality and definition (i HAVE to be able to hear the bassline very clearly in a song with this setup) more than loudness...
My new system: M80s, VP-150, EP-350 and QS8s, Denon AVR-889, Samsung BD-P1500 and XBox360