Need help with Klipsch R-12 sub/settings/location

What are good points to start with the low pass and gain dials on the back of the sub?  At the moment, I want to dial them in with the JBL Studio 590.  I have 2 subs, one for each speaker.  My room is 22'x24', 8 ft. ceilings with 3 big couches in the middle of the room shaped like a "U".  My set-up is against the 24' wall. The JBLs are spaced apart 6.5 feet inner edge to inner edge.  Looking for opinions on room/wall placement/distancing as well.  Though I'm not a basshead, I do like lows.   Appreciate any help.