End of discussion.
Sony does not belong anywhere on this forum, its a pure BAD product with values that are completely off. Dont get this as an insult but your sony will not put out the 1 x 380w @ 4 ohm....
In any case you already have the amp so you will be wanting to use it... I personally would just take two dual voice coil subs so that you can let the subbox play @ 4 ohm together rather instead of wiring it parallel to your amp and running it on 2 ohm.
Look into a low wattage sub with dual coils, maybe the emphaser s3d is something for you, it is a dual voice 12" sub running at 400w rms (200 per coil). Saw it at ACR site for 119 $ each