Thinking I need a Sub...

Oh sure...that makes sense. I'm still feeling good about the REL. If I'm still not happy, I'll just get a good set of full range speakers.

The "total distortion remaining the same" idea from claustrophobic Canadians in the context of REL sub use means nothing. Zero. Does anybody listen to good speakers and say, "wow, if only I could remove the bottom octaves of distorted bad things in my full range-ish mains?" No, they do not. The people who know how to design great speakers make crossovers that take into account the mechanical frequency limitations of the design. The REL dudes know how to make subs, they SOUND great (if set up properly they don't "muddy up" anything), and blend brilliantly with main speakers because that's all they're doing...blending...not truncating or slicing off the low frequencies, but blending in a suplemental way that makes the owners of RELs happier, better adjusted, and somewhat better looking than most Canadians. Most...not all...

I'm not in the Bob camp, in spite of how badly he wants me there. I'm merely speaking about the actual sounds of things, and if you adjust a REL to appear at the point where the main speaker starts to lose its ability to produce much bass and the REL takes it from there (below any main "crossover region" because that is irrelevant to the REL design), it works beautifully. There is no "muddying" of the main speaker's acoustic output because the main speaker is down some serious DBs at that point and (again, based on reality) blends fine if used properly. When you state things like, "The main speakers WILL MUDDY UP the clean bass produced by the REL, at least within the crossover region" you ignore the fact that there is no crossover region at the REL High Level input, simply a frequency point where you integrate the sub to assist the mains, and, clearly, you haven't heard a well set up REL or you would know this (maybe). I know other designs work well also, because I've heard them, and I'm IN the pro recording industry.