Tom,

Spec sheets are guidelines, not definitive answers. The woofer in your speakers is not self-powered. (At least from the information I could find on them) The woofers in your speakers were designed to augment the ribbon driver and to produce the frequencies that the ribbon is unable to reach. I'm sure you get plenty of "bass", however, there is now plenty of musical material out there, not to mention movie material, that utilizes frequencies beyond the reach of your woofers. There's a reason why Outlaw includes a 40hz crossover selection on the 990!

Let me try to demonstrate what I'm talking about. Say you're listening to the 1812 Overture and the canons are booming. Without a subwoofer, the woofer in your speaker is responsible for not only producing the bass frequencies of the instruments in the orchestra but also the rumble of the canons. This canon rumble is "stealing" energy that would be used to reproduce good musical bass. Also, you end up not getting the full impact of the canon. When you add an external subwoofer, you now have your speakers free to reproduce the music while the subwoofer focuses on what it does best, the rumble!

When you bring movies into the mix, the fun really begins. The action gets more intense as you "feel" what's going on. As a side note, my wife loves what our subwoofer adds to movies. Of course, I'm lucky!

Be careful if you do decide to try out a subwoofer. There are many out products out there marketed as subwoofers that really wouldn't help out your system. As an example, your system sounds like it would fit better with an LFM-1 rather than an LFM-2. Both are good subwoofers but your system would benefit most from the added extension of the LFM-1.

It comes down to trying it out. You already have the processor that can take care of the bass management. Now its time to use it!