Why did you not mention Velodyne subwoofers? I would look at a DD 12 Plus. It has both balanced and single ended in/out. It has room and system equalization built in. At around $2,500 it might be too expensive, and that is why you eliminated it.
Subwoofer Decision
I have narrowed my search to two choices though I am sure I will get comments steering me away from these.
Contrast Rythmik Audio 12G with Vandersteen 2Wq. I would like to get only one though I know a pair are best choice. Could maybe afford 2 Rythmik, but only 1 Vandersteen for now. The subwoofer would support Dali Helicons (4 ohms) biwired and driven by 2 mono McIntosh MC 252's at 500 watts each into 4 ohms. Living room size aprox. 24'x16'x8' placement not centered on 16' wall due to furniture (wife) constraints must stay put. Subwoofer placement needs also to stay there as well, I know this limits possible best choice for placement, my bad. There is room behind, next to, and between speakers. Any help help is appreciated.
Contrast Rythmik Audio 12G with Vandersteen 2Wq. I would like to get only one though I know a pair are best choice. Could maybe afford 2 Rythmik, but only 1 Vandersteen for now. The subwoofer would support Dali Helicons (4 ohms) biwired and driven by 2 mono McIntosh MC 252's at 500 watts each into 4 ohms. Living room size aprox. 24'x16'x8' placement not centered on 16' wall due to furniture (wife) constraints must stay put. Subwoofer placement needs also to stay there as well, I know this limits possible best choice for placement, my bad. There is room behind, next to, and between speakers. Any help help is appreciated.