What are you looking for from the sub? Loud, boomy base? Tight accurate bass? Lots of bass or just extended, deeper range? What kinds of music do you like to listen to? If your looking for loud and volume, go ported (2 cubic foot enclosure for the Quants). If your looking for tight, accurate base, go sealed (1 cubic foot enclosure for the Quants).
IMHO, unless your looking for gobs of bass, stick with a sealed enclosure. Shops tend to have generic "boxes" they sell for subs (unless you spend more $$$ for custom). These are not usually an ideal match for any particular sub. Sealed enclosures are much more forgiving than ported enclosures. If a port is a the wrong length, diameter, location, etc, the sound can degrade quickly.
Just my 2 cents
Oooh, and to answer your question.....I've never heard of the Quantums, but the specs don't look too bad.
http://www.quantumaudio.net/
If it was me, I'd go with a Image Dynamics IDQ10 in a .55 cube sealed box, driven by a Soundstream USA354 amp. O, wait, I did...
http://www.sounddomain.com/ride/425503/2