I happened to see an ad on ebay for some Mission 704A floorstanders with built in subwoofers.
There wasn't much to find when I did a search but I decided to take a punt and give them a try.
I notice that other manufacturers - B&W DM605 S2 and Audio Pro Avanti A100DC
supply similar products.
I've not had them for long but I am quite impressed with the results.
The sub can be connected via the pre out of my AV amp and the HF & MF can be connected from the standard front speaker outputs.
A little bit of fiddling with levels is needed but in AV mode the subs knock out some good LF. Having additional bass for music cd's is also impressive.
I think that these will be keepers. However they are big lumps and you need a reasonable sized room to hide them in.
David