Here's my $.02 on this. I'm running Aerial 7B's on the front channels of my home theater, and do a lot of 2 channel CD listening. For the better part of a year, I was using an older, inexpensive subwoofer, for LFE only, and all two channel stuff was run through the Aerials with the sub turned off. The Aerials have been measured to flat to 30Hz by Stereophile, which is lower than they're rated. I recently had the opportunity to buy a demo Aerial SW 12 subwoofer at a good price, which matches the rest of the system. I have A/B/C tested the following combinations (through a Lexicon DC-1, which admittedly is not the best two channel pre-amp), with all subwoofer crossovers being made in the digital domain by the Lexicon: (A) 7B's run full range, (B) 7B's crossed over to the SW-12 at 40Hz, with the sub low pass filter set at various points between 30 and 40 Hz, and (C)the 7Bs crossed over to the SW-12 at 80HZ, with the low pass filter on the SW-12 at various points between 50 and &0 Hz. The SW-12 was adjusted per the manual. First, although the Aerials sound great by themselves, the bass sounds much more detailed and solid using the SW-12. I actually hadn't planned on using it for anything but home theater viewing when I bought it, but it is now used for all two channel listening as well. The best results were obtained with the 80Hz crossover to the 7B's, and judicious use of bass gain control, with the low pass filter set at about 57Hz. The bass in the 7B's melt into the sub in a way that makes it impossible to know if the sub is on when sitting in the listening position. The bass is tight and deep, with none of the muddiness I experienced with the old sub. Also, by in effect bi-amping the system with the sub amp and the Aragon Palladiums which run the L/R channels, I have no concerns that I'm muddying the mid-bass, mids or highs because of power soaking by the bass. I also note that on tracks where the bass is coming from the left speaker, even though the sub is on the right side, the effect is still to anchor the bass on the left speaker, no matter how deep it goes. I believe the higher harmonics still come through the 7Bs and localize the entire bass range to that speaker. It's pretty amazing when you first hear it. So, in answer to your question, I was really happy with my main speakers before the sub, but it's now clear to me that, with a high quality sub, and experimentation with the crossovers, you can have much more control over the bass and greatly improve the overall sound. Jeff