Great sound possible using a Subwoofer?

Nick, play a test VCD with third octave pink noise, listen in the listening seat, and see if your pseakers really are flat to 38 Hz in your room. They might not be.

That's CD of course, sorry for the typo.

If your speakers are flat to 38hz, you should have absolutely no problem with bottom end weight of your program material. There are really very few instruments which reach that low, anyway. Two are the piano and the pipe organ. If your system goes that low, it should be rattling the floor. Also, rock music, while often filled with a lot of bass, is usually not very deep. Most rock music is rolled off well before 40hz. A good CD for testing the bass capabilities of a system is Sarah McLachlan's "Surfacing". If track 2 does not shake the floor, your speaker manufacturer is lying to you, or you have some bass extension problems upstream in your system.

In many ways a speaker that goes down smoothly to 40Hz is an ideal candidate for a subwoofer. It's much easier to crossover from the sub to main speaker if the main has reasonably deep bass response. It allows the sub to just work the deep bass without having to work up into the mid-bass region. However, most popular music doesn't have alot of content below 40Hz. A typical pop mix hypes the 80Hz region in lieu of deep bass, so you shouldn't expect to hear a subwoofer on all music. In fact, if the sub is correctly setup, you shouldn't hear it all that often. But when it hits -- you should feel it. None of the other changes you're considering will do what a good, well setup subwoofer can.

I think the real issue here is what type of amplifier are you using? Accurate reproduction of low frequencies requires a lot of power. This is why most powered subs will have dediacted amplification of 200 watts or more (preferably). Adding a well-made subwoofer to your system will free up your main amp and allow your speakers to open up. HOWEVER, for the same expense of a good subwoofer you may want to consider a heftier amplifier. It sounds like some experimentation is in order. I went with a subwoofer to get that extra low-end punch but a lot of my decision was based on the fact that I wanted to have a HT set-up also.