Hooking up my JL sub

@millercarbon. Thanks BTW. Stupid question: is there a decent grade LOC unit that you recommend? Also, a few I saw online have a bunch of color coded wires sticking out. Which wires connect to the R/L of the amp speaker output. 

@millercarbon. Thanks BTW. Stupid question: is there a decent grade LOC unit that you recommend? Also, a few I saw online have a bunch of color coded wires sticking out. Which wires connect to the R/L of the amp speaker output.

Hard as this is to believe this is one where quality does not matter- other than aesthetics, cheap looks cheap- you will never hear the difference. 

I had to learn all about this earlier this year when adding a distributed bass array. My tube integrated amp had no sub or pre out and the Dayton sub amps only accept line stage inputs. So after learning about this I made a simple mod to the amp, and with a couple cheap resistors converted one unused RCA input into a stereo sub out.

Again, because I know nobody will believe this, but go cheap, it just doesn't matter. Another one everyone loves to argue, but its true, don't need both channels because all the low subwoofer range bass is mono. So if you care a lot how it looks and are willing to mod then search for line out converter circuit or let me know and I'll send you the link. Otherwise buy the cheap one at PartsExpress.com

You do this and if I understand your system nothing needs to change, just connect the LOC to the speaker on the Marantz, leave the existing RCA connected to the sub but move the other end to the LOC and the sub will now work for everything.

Piece of cake.

Thanks for the info again. 

Quick question while we’re on this topic. Would connecting a sub using an LOC from the power amp not pass the entire range to both the speakers and sub? Would there not be a double bass effect? 

Yes. That’s why the preferred method is using a line level connection which both passes the sub info to the sub while removing this information from the mains.