@Sparkus... Pogre is pretty much on the money with your conversation. Unless you have true Full Range speakers (most of us don't... my mains are close, but still not quite there) you will benefit greatly from having subs. I use my towers with subs and am very happy with them for Music. I was very happy without the subs too, but I do indulge in some Electronica and Pipe Organ, both of which can easily push my Speakers beyond their limits. When I adjusted my crossover to that point where the speaker is comfortably transitioning to the sub, I was rewarded with greater clarity in my Mids, and better Bass. Not that my tower was lacking, per se, but with the added extension and focus of the Sub, my towers were freed from having to reach for that extra little bit.
Moreover, by having two matching subs, larger than my room requires, I also benefit from not having to push any part of my system too hard. My Subs are very capable, yet I'm only using about 1/4 - 1/3rd of their capability! Even at louder SPL in my room, I'm never pushing these to anything close to a distortion point, unless it is in LFE programming that might go lower than they're capable of effectively reproducing (15Hz, in my case).
One other comment that really resonates with me is that, for most music, the subs don't have to be cranking. I've actually backed my subs off of what Audyssey sets. For most music, the Subs are too hot. Upright Bass in a small Jazz Combo shouldn't be vibrating the structure!
Definitely, Subs are an integral part of the overall system. Employed with care, they are present, but not in your face unless you choose. They do take some work, but learning about acoustics and how all this stuff works together in an integral system is a worthwhile pursuit. The sooner you embrace that, the better your system will become now... And when it comes time for you to choose the upgrade path, you'll be placed even further ahead!
Cheers!
