I noticed something about the SVS box subs. The dual woofer models have tunings of 25, 20, and 16 Hz. And the single woofer models have tunings of 20, 16, and 12 Hz. Is there a specific reason for this? I can't remember the order that the box models were released, but I think the single Ultra came out after the dual Ultra. I wonder if it is a logistical decision? Would a 12 Hz option for the dual woofer models mean a much bigger box? I bet there are some bass fanatics who would love a 12 Hz tuning on the PB12-Ultra/2. Thoughts? Ron and Tom?