Your good to go with what you have . The amps in the Mythos and the amp in the JL sub will leave your more than adequate Denon to do the mids and highs which are alot easier on an amp to produce . The center channel reproduces the vast majority of information for home theater anyway. Seriosly enjoy what you have now . You might even want to try your set up without the JL sub first . Watch a few movies play some music then add the JL sub and see if it is an improvment or a problem . Have fun and enjoy, you have some nice gear for home theater use . Cheers