Hi; I have used my Super 5's with my homegrown T-Line subs with 10" Focal Kevlar drivers. I found that in my room a X-over @ 80Hz was the best, and my Marchand 24Db/octave unit is easily adjusted with resistor blocks. Very clean and quick transfer from subs to 5's, allowing the 5's to operate without severe bass demands, freeing up the lower mids. The whole system goes down to 24Db at the -3Db point in my medium LR.
Cheers, Hank