Would adding a separate 3 channel help in this situation

You should look into the built-in compression settings.  I'm not sure what it's called but you can reduce the dynamic range.
Also, while the ARC is pretty good, you might want to boost the center channel somewhat.
Of course good room acoustics help. :)

Just get a compander. Movies are mixed for big rooms like theaters.
Even a Terk VR-1 will help but you can do much better.
OR   
Move into a barn.
I cannot fathom how adding an amp & speakers would limit dynamic range.
Enlighten me.

I am curious about this as well...same aggravation with the cohabitants here.  I have an upper end Marantz Receiver and Focal 936 and other Focal in wall/ceiling speakers, all calibrated through the room correction.  Voice levels are not quite loud enough so up goest he volume...until the effects start going off and then it is too loud for the others.  This is MOST notable when playing UHD.  
Per the other poster, I probably just need to bump up the center channel...not sure why I haven't done that yet.  
To the OP, my first inclination was to get better amp for this system...hahah..probably need to do that anyway as that is what this hobby is all about.

Ah, Erik, that's an excellent suggestion.  I forgot about that.  Looking at manual, the Anthem has a "DYN" button on the remote.  Just hit the DYN button twice, then you can choose between 3 dynamic range settings:

NORMAL: No dynamic range modification.

REDUCED: Allows the quieter parts to be heard more easily by raising the level of quieter sounds and/or reducing the level of louder ones according to cues in the soundtrack.

LATE NIGHT: Further reduces the softest-to-loudest difference

I'm sure you can play with these to determine which one is best for you.


Also, asnumcwrt2 suggested, try bumping up the center channel by 1 db.  You would be amazed at the increased vocal clarity when you do a 1 db or 2 db adjustment on the center channel.  NOTE: this may put the center out of calibration based on keeping it exact as the left/right/surround, but I have seen an increase in understanding dialog when I do this - and it really doesn't detract from any sound balance.

@numcwrt2 - Marantz receivers has the dynamic range compression feature as well.  If you go into the setup menu, it is under Settings => Audio => Surround Paramater => Dynamic Compression.

You should play with the Low / Medium / High settings here.