Thanks everyone. I think I am almost ready to pull the trigger on the DD12. I do have one question though... I ran a frequency sweep of my speakers with the REL off. While I did not record the results exactly, the things that stood out were:
1) Bump of 4-6 db between 80-95 hz
2) Small dip in the mid-to high 100s... maybe 170 hz? Do not remember and I cannot confirm right now.
3) Rapid rolloff from 55 hz down, to about 6 db down at 40, pretty much nothing there after 37 hz.
Also, I am running an integrated with a subwoofer out feature, which is placed AFTER the volume control (so the SW follows the amps volume). With the REL, I have been using the high-level (Neutrik) connections out of the amp's speaker posts so I have not had to worry about any of this.
Given the points above, is the DD still the way to go to correct all the bumps and dips, and will it do all it is made to do using the connections I have now? As you can tell, I am a bit illiterate when it comes to advanced SW connections, not having had to do so for a while. I am not a technophobe, and am sure I could learn how to set it up, so that is not an issue. But I just want to be sure, before laying out cash, that I can realize the full potential of this impressively-spec'd machine.
BTW, I will be using the sub in a strictly music-only, 2-channel system... does that change any of the answers above or any to come? Sorry, should have stated that earlier. I do like the individual settings feature, so I can use a different one for rock, classical, etc.