What do you mean "Power the Epiks with your Rotel"?
You can't add power to a self-powered subwoofer.
Edit:
By the way, about "circumventing the internal amp". I've done it with success on 5 subwoofers. First was a JBL DPS12 that I bought at a garage sale for $5 cause "it didn't work". Took 10...
There are some receivers that do, finally, have actual separate sub outputs...not just an internal "splitter"...very few and far between.
You might try a DIY on your current Klipsch. Remove the plate amp, bypass it and run it with a dedicated external amplifier(like a Dayton "bread loaf")...