Use of subwoofer with bookshelf speakers


I heard demonstrated a Pair of Canalis Anima speakers and they were awesome. I'm using full range speakers now (ML Odysseys) which have developed a significant problem and am considering purchasing these Canalis speakers when I can put together enough money to do so.

My question has to do with using these with a Vandersteen sub. Vandersteen recommends using this sub with speakers having effective capability down to 40 Hz. I think the sub has an upper cutoff of 250Hz. Will I be able to use them together and have an acceptably smooth sounding transition between them?
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For music, the Rythmik sealed subs look really interesting. Due to furnishings, I've been limited to small speakers for a while. Over the course of the last year or so, I've run System Audio 505s, Paradigm Studio 10s and am now running a very small pair of Silverline Minuets. The are all good sounding speakers that are fast, but need help with the lows.

I've run a little REL T3 with them and it's been easy to integrate and keeps up with them very well. I've seen them go for around $300 or so, if you can find them. Heck, for that low of a price, you could get two and have stereo subs.
I have the Sonics Anima -- very similiar to the Canalis version -- paired with a REL Strata III sub, and they sound great together. I had been using the Animas sans sub for a few months and mostly didn't miss the bass <60hz, but then I got the sub and really noticed what I was missing. The sub fills in that last bit of the picture and adds more scale. Get a sub (REL or perhaps an Audio Physic one would fit nicely) but first get a good pair of 24" stands.
However...I believe Vandersteen( and others) recommend crossing over an octave higher...so full range speakers would be x-over at 80hz...most speakers are -3db down or more at their LF cutoff point...thus the rationale for x-over higher...and anything above 80hz is usually directional in nature...hence the full range recommendation...