Okay, into 3808 sub out you can plug this , then this to the TRS adaptor and into the sub amp. As far as the speaker wire, I'll point out(at no extra charge)that you don't really need 12ga for those lengths and 14ga would do the job, as the Russell article indicates. Here's some 14ga , for example, depending on how much you need in total.

You know, Demetrios, after preparing all these links, it does seem that you're a bit of a pita(just kidding!).

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Enjoy the music, not the equipment.