McCormack .5 with Vandersteen 2CI

0.5 was plenty loud in my 23 x 14 room w 2cis. Great match.

I'm using a Belles 150A Hot Rod with Vandersteen 2ce Sig2's
mated with Audible Illusions 3B preamp. Great senergy. The Belles with a tube preamp is a great combination with Steens.

You should have your co-worker stretch a bit and wait for a 0.5 Rev. A to come available. It'll probably only be another $200 or so more expensive and is at a completely different level than the stock or deluxe version, and the Vandys will certainly take full advantage of the improvements. Best of luck.