Should I bother to try a subwoofer?

As a former full range speaker user and subwoofer hater (except for pro sound use) I found Elizabeth's comments understandable but less valid than usual when applied to a topic including REL subs..."Rock" music can certainly have a lot of bass (as does a lot of the jazz I like...Brian Bromberg anybody?) but the beauty of most RELs is the amount of gain, phase, and frequency adjustment inherent in their design. I adjust the output level frequently (in small steps...I put a "chicken head" amp knob on there so my greasy little fingers can "feel" what I'm adjusting) to fine tune the bass response for certain bass shy or bass bloated wall shaking recordings (do I agree with ALL of the engineering decisions made by the faceless strangers who messed with the sound of my recorded music? NO!)...otherwise impossible with my (and most everybody else's "high endish") preamp. It's nice to be able to do this while leaving the rest of the signal chain and main amp signal unmolested, as, for my tastes, this is all the adjusting my rig needs...plus it allows me to continue my sonic dominance over these things as, after all, I am the "decider".

Yes, get a sub and set it up as others have said here. Keep the volume low and cross it over low - no higher than 60 htz and 40-50 would be even better.

The stage will open up just as Teajay stated on the first post. Please read his post again. He is spot on and very wise on the topic. I use a Velodyne DD18 sub with my Soundlab M1 speakers and I set them to only handle 16-50 htz or so. The volume is set very low and the improvement is wonderful.

Larger stage, more 3D sound, a foundation and scale not achieved without a good sub. The improvement is HUGE when done right. Avoid the corners of your room, instead place it anywhere between your speakers at a plane just behind them with the sub shooting at a 45 degree angle into the room - if a front firing sub.

Avoid turning it up to much or crossing over to high as these things will ruin the mids and call to much attention to the bass.

The REL sub is fine and will give you a taste of what a sub can do when set up properly. It is down firing and smaller, so closer to a corner is OK, but my suggested set-up could yield better results.

Knowing your room size etc... would help greatly.

You could always pic up a second one for more improvement as one becomes available and you decide you love the improvement that ones gives.

My REL Q150E is side firing.

My REL Q150E is front firing. It sits in a little corner made by a fake fireplace behind the left speaker (firing forward toward the back of the main speaker) and that is EXACTLY where it belongs in my room (I moved it all over the place and pointed it in various directions until it seemd to lock into its current spot).