@scott22
Yep you just have to play around with it. Sub positioning and adjustments in terms of cut-off and gain is not an exact science, as again, every room is different, and also the speakers you are 'marrying' them to.
As your Canton's dive down pretty deep, I would not think you want the Jamo set much higher than 60, and I'm just guessing, but lower is probably better. But again, gain and placement all come into play.
Im sure your wife would want them to disappear ;-) So, you may be more limited in it's placement. Just do the best you can, and try a variety of different things. Believe me, this could take a while, so be patient.
Also, for music, don't discount the feeling that the sub itself is not doing much. That can be a good thing, and turn it off, listen, then back on to see differences it may actually be making. Pick a good wide range dynamic selection.