Connecting sub to Yamaha CA 810

Appreciate some guidance on what is probably a simple question.

I am considering connecting the 810 to a Paradigm cinema sub that has only line in (L+R). As the amp does not have sub out option would it be best to run an extra set of speaker wire to the sub from speaker outs (ie have 2 sets of wire in Speaker A left, and 2 in Speaker A right, one set of wire running to the speaker and one to the amp)?

Thanks in advance for any help!
Lots of folks prefer the speaker connection to a sub. I also think you can use the Yamaha's pre out jack.
I'm interested in the responses you get because I just connected my sub two days ago exactly like you described. I'm wondering how that changes the load that the amp sees.