Should I bother to try a subwoofer?

Yes, you are missing something, especially with classical music. Try a sub, but don't cross it over too high, and don't turn it up too loud. If your monitors are rated down to 40 Hz, try crossing over at 45 and 50 Hz. With good recordings and good components, you will hear and mostly feel exactly what you are missing.

If you were thinking of buying any other subwoofer besides a REL the results would be questionable, but REL subwoofers don't sound like subwoofers. A REL will produce clean musical bass that will complete your system. You won't believe what you've been missing. Granted, your Dynaudios may be rated to 40Hz, but those little mid/woofers just don't move much air.

You've got nothing to lose. If you don't like it REL's are easy to sell. I say go for it.

Try the REL subwoofer, as I did (with a REL Stentor). I think you'll be favorably impressed with the bottom octave as well as the improved soundstaging (as stated very well by Teajay). If you don't like the change, there are lots of folks who like the REL, and you could sell it easily if it's in good shape. By the way, I'm a music-only listener.

the Rel, which is a GREAT sub for music, will add a lot to your musical experience. Try crossing it over at 55hrz to start and go down from there.

I had a Rel B1 that I used with my Maggie 3.6R's (measured down to 34 hrz, about the same as your speakers), and I ended up with the sub crossed over at about 42 hrz, and not turned up too high on the gain, and man, what a difference.

I currently use a Def Tech Supercube 1 with my Maggie's crossed over at 40 (lowest setting), and once again, it's just sublime to add that sub for the lowest octaves.

Good luck.

"Need"? YES YOU DO! I'm a huge fan of the REL stuff for hifi. A friend turned me on to 'em a year or 2 ago (he has the same main speakers as I do). I bought a clean used one (Q150E) and man...anybody who smugly claims there is "no benefit" from a well designed sub instantly destroys their audio opinion credibility and shall be forever removed from my christmas card list. Read the current issue of "Absolute Sound" for a nice REL review...I've done the experiment of turning the REL off and on to see the difference, and when off it dramatically diminishes every aspect of the overall "life" (tonality, soundstage, dynamics, odor) of my system.