how to connect RCA subwoofer to monitors? (with pics)

Hi guys,

I want to buy an audio interface and cables that will get this set up working - I have an old sub (Wharfedale Powercube 10a) with RCA ins and outs:

Attachment 28420

And new monitors with RCA and TRS inputs:

Attachment 28421

Can anyone recommend me a cheaper audio interface that will get this set up working and the cables needed to go from
audio interface > RCA in on sub > RCA out on sub > TRS or RCA input on monitors

Would I run a single RCA from the left out on the sub to the left monitor and the same for the right?

Attachment 28422

What is your music source right before the speakers? Are you coming out of a mixer?

you can run it all on rca's!! mixer to inputs on the subwoofer, and then speakers to outputs on the sub!!! then you just have to adjust the crossover to your liking.

i run rca out from Booth monitor on my mixer so i have a dedicated bass volume knob