I agree with Bob Reynolds here. You have to look at the bass rolloff characteristics of the Canalis to correctly match it to a subwoofer. He's also correct about the Vandy's crossover slope of 6 dB/octave. Here are the specifications
One thing the Vandy has going for it is that it uses 8" drivers, giving it a higher ratio of flux density to diaphragm size, which is better both for transient response and for less cone breakup. With a 5" woofer, you want a subwoofer with great acceleration--transient response--to keep up with the 5" woofer. The Canalis 5" woofer is aluminum, so it would be particularly fast and rigid and need a fast sub to keep up. Not too many subs are great at both matching to mini-monitors for music and also having the bass extension and dynamic range for home theater. It appears that the Vandersteen was designed to cover both applications, and the gentle 6dB slope should make blending it with the satellites a bit easier.
If you didn't already have the Vandersteen (I assume), I'd recommend you get a pair of small, sealed subs. I match a pair of (now discontinued) Mirage MM8s with my Mirage OMD-15s. The MM8s are 9" cubes housing an 8" aluminum driver augmented by two 8" aluminum passive radiators. They don't go very deep, but they are very easy to match up musically with bass-shy speakers. They have lots of power and a crossover that can be adjusted from 50 Hz to over 200.
Although the Mirages are discontinued there are several good small sealed subs with similar configurability. They're easy to blend with decor and match up with small speakers well, but they generally aren't designed for room-filling 20Hz bass as the Vandersteen is.