Expert and basic subwoofer setup & configuration

[Laura]

Thanks guys. I really appreciate, as always, the rapid and helpful responses. @Axel, thanks for the diagram of the config; saves me continuing to guess, and stutter and mumble and swear to myself as I get tangled up in wires.

@thumb5 I don't have a particular specimen  in mind. But constraints are size and location. The sub would need to be off to the side of the left speaker, facing across the front plane of the Dalis. That may be too compromised a location, and if so that would be the end of it. But as I said, I'm really looking for a modest extension of the bass, rather than thunder.

Using Canuck Audio Mart, (CAM as it's usually referred to) is a good marketplace for buying and selling used equipment, and that is where I have been looking. Two listings have my initial interest. The first, from Craigslist, is a  PMC sub and the second a custom scanspeak sub from CAM. Both are very local to me, which is a bonus. 

Certainly a fuller range speaker (?) would do the job, but that then puts me back into the big boxes that need storage, both while we are home, and then when we are away. I just wish I could find something that is very compact, not an adolescent thumper and yet more than a toy that comes with computer speakers. 

Finally, I realize that I'd give up SAM, which I really like with the Dali's. I may well be put off this pursuit fairly quickly but I want to be more informed either way. 

Thanks friends.

No need to give up SAM, it's not a one or the other scenario. If you need something smaller then have you considered a REL S3 SHO or it's replacement the S510? It needs to be something that is commensurate with your current system and room size for best performance, a cheap subwoofer will likely just give you that uncontrolled boom that you want to avoid. I think you also need to stop looking at this from a point of view of just low end extension as a well set up subwoofer will improve the sound across the lower ranges, adding texture to voices and instruments and when properly integrated the difference in sound will amaze you. It's a slippery slope though as once you've integrated a sub it's hard to go back.