What percentage of audiophiles use a sub ?

Incidentally,

You don't want to measure the distortion in the bass on your (or any other) monitor. I'd direct you to any of the subwoofer forums, but the results might make you queasy. Suffice to say that even specialized 8" drivers tend to struggle below 50hz at volume. The large cone (12",15",18"), drivers in the better subwoofers will typically produce about 1/10th the THD of the best 8" drivers at highish SPLs <50hz.

Pre-empting any comments re: "speed" in the bass, I'd personally look to group delay measurements (which tend to correllate with damping rather than driver size), but I'll acknowledge that some feel that these don't tell the whole story.

Mapman - "I have yet to hear small monitors that can compete with equally good full range speakers for delivering the oomph that some music requires."

No argument there. I love full range speakers, especially the Reference 3A. For an apartment dweller I just couldn't go full-range and found my monitors to be more than satisfying. But even then, with a full-range setup I still would not consider a sub. Again, that's just me. My car is a different story. I like it heavy and low and my JL 10W7 gets me just that. ;-) But then I'm not aiming for perfection in a mobile environment.

Tigger,

I will just add that I do think adding a well matched powered sub or two to monitors is quite capable of doing it all well and often at considerably lower cost than most single box full range speakers combined with similar suited amplification needed to match a powered sub.

Plus from the perspective of setup flexibility and convenience, a separate powered sub for the low end helps a lot. Proper setup in the room is key to performance. Often there are things that prevent people from accomplishing optimal setup with big massive single box speakers in many situations. They are just too heavy to move or experiment with easily so people do not bother as much or the placement options within the room is just too limited to get it all right including the low end. When this is the case, there is a very strong case to be made for offloading the bass performance to a dedicated device (a sub) designed to handle only that.

Also, yes, good monitors (and also perhaps a good set of headphones) are often just what the doctor ordered for apartment dwellers.

It is all a matter of critical system matching between components and taking the time with the room set up. There is much music in the 80hz region and below, not just movie soundtracks. For those who have a powered sub(preferably 2)that has the connection choice of rca in or speaker level in, I find the speaker level in is much more coherent with the mains. I learned this from Pierre at Mapleshade many many years ago. The quality of the speaker cable is as critical here as with the mains. Crossing over the mains or running them full range is also very system/listener dependent. I run my mains full range and have the bass systems from 60 hz down. Adds another level of musical realism to these ears......