how to integrate svs active sub into my unico hybrid 2 channel integrated receiver/HT

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I have a Unico Hybrid 2 channel integrated receiver (see www.unisonresearch.com for more info..it's the 'hybrid' at 80 watts/channel), a Sony 999es dvd/sacd player and a pair of Devore Fidelity Gibbon 8 speakers (i'm also selling a pair of 5 yr old B&W matrix 805 series 2 bookshelf monitors with stands for $900 OBO).

I recently had a pair of l/r full range preamp outputs installed into my Unico Hybrid integrated receiver to run a pair of subs...then I bought the SVS 20-39pc+ active sub.
(here's a pic of the back of it....http://www.svsubwoofers.com/images/...s500closemr.jpg)

It was suggested AFTER i got the preamp outputs installed that i wouldn't need them as i could run a pair of speaker wires from the unico's speaker outputs into the l/r sub's imputs and then a pair of speaker wires from the subs' l/r outputs into the speakers...this way it'd be not just intensifying the signal (which the preamp hookup would only do) but also by switching the crossover frequency to 80 I could take the load off of the speakers and thus let the sub do its job properly.

Now what about if I want to use a pair of mission 731pro bookshelf speakers I have as rear monitors for HT?...someone suggested buying the Denon 3803/05 multchannel processor receiver and using this WITH the Unico Hybrid, but some one else said that would not work
(I had the Unico modded by chris johnson/parts connexion so it is expensive and a gem)....

So I may wish to go to 5.1 without dashing my unico?

This area is new to me so pls keep it in mind if you can make some suggestions.
cheers
joe