That depends on how your amp is setup. If your amp has a separate crossover control for the sub itself (that doesn’t affect the mains), then setting the amps sub output to 120Hz and the sub to 60Hz you’ll be fine. As long as your amps separate control for the mains (if it so has one) is set to give the mains 60Hz and up, or you’re letting the mains take everything then your fine.
But if your amp is like mine, and it only has one crossover control for both mains and sub in one setting, then your right and you’ll not want to setup your amp like that. Then you’ll want to try Ian’s alternative and you should use the 80Hz setting on your amplifier and the highest setting on the EP175.
