Yes, you can use the AVR subout to LFE for movies and the integrated subout to Line In for music on the Rythmik subs.

This has been confirmed by Rythmik as I asked because considering the same set up.

Either this or a variant via my miniDSP (AVR out to input 2 on minidsp, music preamp to input 1 on minidsp). MiniDSP outputs to subs lfe-in (most likely as can do bass management in the miniDSP, and set up different configurations for music and movies).