Ok, I called Audio Research and talked with Leonard in the service department. I think he's been there forever and remember speaking with him maybe 15 years ago when I first got this equipment.
Anyway, he basically said to go ahead and hook-up the dual speakerwire set-up. He did confirm that the "Tape Out" on the pre-amp would not provide any volume. Said to double the wire L&R for both the main speakers and the sub.
There is a warning in the Sub manual saying the amp must be common grounded for this connection, but Leonard said that's fine and not an issue. So I'm going with the dual speakerwire config and let you know how it goes.
Anyway, he basically said to go ahead and hook-up the dual speakerwire set-up. He did confirm that the "Tape Out" on the pre-amp would not provide any volume. Said to double the wire L&R for both the main speakers and the sub.
There is a warning in the Sub manual saying the amp must be common grounded for this connection, but Leonard said that's fine and not an issue. So I'm going with the dual speakerwire config and let you know how it goes.