ACE by Moon bypass function

I bought the Ace to improve sound quality for my ProAc tablettes when listening to music.  And still use an old Marrantz slim N1402 for movies, TV utilized not the bypass feature on the ACE.  Music sounds great, watching TV with just the fronts sounds great but when I am using my traditional TV set up of 3 channels (in a small condo so no surrounds) the center channel now sounds awful.  It sounds as if the dialogue is in a tunnel or like an old am radio mono signal.  I tried the Audyssey speaker calibration and all that did was increase the center channel output level which makes it sound worse.

I was thinking the ACE by Moon is overpowering what the Marrantz can push on the center channel or the center channel now needs to be upgraded to something that will be more in line with the sound quality of the ProAc tablettes because the ACE is getting more out of the speakers than the marrrqntz.  

Anyone have thought on the issue.  Things to try out before spending more money on another AVR (defeats the purpose of why I got the ACE and not a new AVR in the first place) this is begin tearing out new center channel speakers?  

My center channel soeaker is ablut 10 years old and is still maids a custom cabinet so It’s hard to get to and I can’t remember the brand but around that time I bought PSB bookshelfs and it was not that brand but probably in that price point quality range.