does a subwoofer kill stereo sound?

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.

Ohjoy40...I respectfully disagree with your comment. The bass that comes from a sub IS perceived as mono..whether stereo recorded or not. Bass is non=directional. What makes it seem like stereo, are the overtones, not the 30 or 40 cycle fundamental. These overtones are reproduced by the regular speaker, and thus seem directional. There is no need to spend lots of money on a "state of the art" amp to drive a "state of the art" sub. The built in "usually" class D (big power vs small size) is very good...the sub has a very limited range, without need for those subtle nuances we all love to listen to on our full range speakers.

Martykl...Actually, I hear it quite differently. If you have a system that can accurately reproduce the lowest frequencies accurately (I am not commenting on your system) you will clearly hear low end pitch differentiation on those very powerful low notes. This is clearly the work of the bass player. Yes the drummer's kick drum adds some concussion when appropriate, but those lows are clearly the work of the bassist. I further speculate, that it is an old Kay plywood bass that's been electrified, and plugged directly into the recording board. In the song "Day Dream", the bass starts the tune, and the drummer comes in a couple of measures later.