does a subwoofer kill stereo sound?


I was wondering whether adding a subwoofer to a pure stereo system would cause any harm to the soundstage and other features of the system. What are your experiences? Should one buy a subwoofer to complement a great bookshelf pair (that may be lacking some bass) or necessarily one would have to buy a new par of speakers with deeper bass?
tvfreak
I find the contrary to be the case, provided you have a good sub, properly integrated. The deep bass opens up the sound stage a lot as compared to a stereo that rolls off at ~50hz +, and in no way degrades the stereo separation or imaging.
When I shut my sub off, the stage gets narrower.

Sub is playing well with panels.
One of the best things you can do is add a powered sub or subs to a system. If done correctly, it frees up the amp to power the mids and highs adding much better performance.