Thanks for the reply.Go ahead and set both to flat.
Unrelated to the sub settings, but if you still find it bright increase room gain.
When you change the cutoff frequency for the mains in the ARC software it usually moves the crossover frequency in the Anthem speaker setup menu to match. (You should not touch anything in this menu or you will break the ARC solution.) Like Bob said there is probably no point in lowering the cutoff if you have a good sub. This will put more bass requirement in your mains and yes, to answer your question, it will send less to the sub. It won’t affect the LFE channel; that always goes entirely to the sub.
In my system lowering the mains cutoff actually had the opposite effect I was expecting: it made the bass more boomy instead of tighter.
When you say "(You should not touch anything in this menu or you will break the ARC solution.)" which menu shouldn't I touch? The one I was referring to? The one you mentioned had exact opposite results?