Pauline -

If you're looking for "concert sound" to sit back and listen to, and really need to feel like you're in a concert hall (or a mosh pit) then those numbers about frquency response and signal to noise etc actually do have some meaning, perhaps.

If you just want some music while you're using your computer, unless you're among those who must have "bass you can feel" at all times, most will find that a simple pair of satellite (stereo) speakers will give reasonably good sound quality and sufficient stereo separation for enjoyable "background while working" music.

Except in rare cases, modern commercial CDs do not record any musical sounds below about 50 Hz, so worrying about rolloff below that isn't particularly worthwhile, if you're interested in accurate playback of what's on a CD. Very few FM radio stations deliberately broadcast signal components below about the same 50 Hz. If you're a long way from the station, there may be lower frequency content in what your receive; but it's largely transmission noise picked up due to the distance from the station.

Adding a separate bass "woofer" channel to your playback system allows a little more flexibility in adjusting the amount of low frequency content to suit your own preferences; but if your preferences demand enough bass boost the really benefit at anything less than "concert hall" playback volume, you can probably get the same effect by rearranging the furniture so you can sit on the clothes dryer while you work. If you're listening only at concert hall volume, you should limit your listening to no more than a couple of hours a day, or you won't hear anything at all in a few years.

John