depends on what you listen to. The Tennessee Bassoon Quartet will exercise your subwoofer. Cecilia Bartoli probably will not, depending on the accompaniment.
That's the main reason I went with a smallish 2-way floorstander instead of my first love, which is a smaller bookshelf monitor. My new mains will hit down into the 30s, which is plenty for me when it comes to music. That way I can calibrate my mains for HT, and then run my Denon2900 uni player through the bypass on my pre/pro full range. Sounds great
Okay, the thing is that it seems that the accoustics of my room aren't that great. I don't have a subwoofer and it seems that the bass is stronger in certain parts of the room. I mean, in certain parts of the room (and room is fairly small) it sounds like there is no bass at all where as in other parts the bass is strong and punchy. This is true mainly for music.
However, for movies, the bass seems strong everywhere. Also, it seems that the system produces more of a punchy and defined bass during the earlier parts of a movie (like when the system is cold). Is it true, the sound slightly alters when the system warms-up?
In the main system I use stereo subs but they are Rels so that have separate inputs for home theater and music. For music they take the signal from your amp, have its own crossover and volume control. By main speakers are full range so they are crossed over at 22HZ. I have an RTA to measure where there are problems and have sound treatments in the room (incl. 6 bass traps). The best thing to do if you don't have an RTA is get a test disc to use with a SPL meter. Rivesaudio.com makes one that works with the Radio Shack SPL meter, there stuff like http://www.delosmus.com/cgi/cart/ite...18581145410989 or sites like http://mdf1.tripod.com/test-tones.html where you can get free test tones. Once you know what the problem frequencies are from the listening position you can compensate with either sound treatments (could be natural stuff like wall coverings too) and/or moving things (e.g.) listening chair, speakers, sub, etc., depending on your preference for movies vs. music. Sometimes optimization for one is not optimization for the other.
For me, its a room acoustics issue. Being able to optimally place the sub to do what it does best, and optimally place the L/R pair for them to do what they do best, and being able to EQ the sub w/o messing with the main channels represents a huge improvement in overall sound quality.
Now, if I lived outdoors, or had a room that was the size of a typical civic center, then no, I would go with a big-ass pair of real full range loudspeakers.
But since I prefer indoor living in less than palacial size rooms, its a 2.1 system for me (and a 6.1 for my HT rig).
I use one in both systems (HT and sep music only system). My HT setup lets me have different levels according to source, so that works out well as I find myself listening to more music on that system (since I upgraded my fronts). Of course it's not an issue for the music only system. I use to run what I considered to be "full range" speakers but have since moved to smaller monitor style speakers. For me they image better and with the sub I still get the full range I'm looking for.
I use a sub for everything BUT 2-channel stereo. My mains (Infinity IL-60s) are down 3dB at 25Hz so for everything but the most demanding organ music they do it all. And quite well. They are the fourth set of speakers in 18 years to grace a 13 x19 room. And the first that I felt comfortable taking the sub out of the loop.
I use a sub with music 95% of the time. The other 5% of the time I forgot to turn the sub amp on and it's something light being played as background music so I don't notice.
I use B&W 804's, previously used paradigm Studio 100's, and my experience has been consistent; with the sub on, the sound is more connected and just sounds bigger. It's funny b/c if I turn my mains' amp off (the sub amp is still playing) there is barely anything coming out of the sub.
As far as people saying that music doesn't have much info below 30hz... I disagree. Maybe not much large scale info, but there is plenty there, of course this will depend on what you listen to....
I prefer to listen to music created when the production of infrasonic sound sorely tested the ingenuity and engineering mettle of musical instrument designers.