Subwoofer

bondmanp,
I think what he was saying is, no matter what the listed frequency response of a speaker is, in his experience all speakers benefit from using a sub.
The question is, will spending an equivalent amount on better speakers yield similar results as adding a sub?

The beauty of a subwoofer is in it's ability to be placed in the best location for your room . Your mains are restricted in a fixed immovable location due to a triangle listening setup .

the difficult part of subwoofers is not messing up the upper bass, lower midrange...

If you want helicopters in your listening/TV room, a sub is wonderful. I have experimented for years and prefer no sum except when required for extra bass impact. All salesmen say that anything they sell helps.

danvignau,
I'll repeat what stringreen said, " You're not extending the low end, but making mids and treble better." That's has been my experience with my current set-up. My soundstage has opened up, mids and treble has better detail.