OP, here is a review that I think you will find helpful. It even addresses how efficient the Vandy 1C's are. Easy to drive by your system or if you ever upgrade it will keep sounding even better as I was trying to point out. Your dealer will help you with the set up to get the most out of them. Very easy to do.
http://www.tonepublications.com/review/vandersteen-1ci-loudspeakers/
http://www.tonepublications.com/review/vandersteen-1ci-loudspeakers/