have only speaker level out to sub ... svs micro3000?

I have the Marantz Ruby amp, which is all analogue and has no pre-out nor sub-out jacks.... I'm interested in the svs micro3000 but it doesn't have speaker level inputs.  Is there a work-around?  

In my situation, I'm attracted to the dual-sided concept and the small form factor.  And, I like that svs subs have app adjustability for output and eq etc.  

I'm currently using a fine Pinnacle Baby Boomer, and it does have speaker-level inputs (and of course outs then to the speakers), it's dual sided... pretty nice, actually, but I'm interested in the new app tech and greater adjustability.