Evolving from a avr to an av processor. Benefit?

I don't think the AVR vs. AVP is a big deal so much as who is doing the processing.

Do listen to the Anthems. I like the sound a lot better than Marantz.

I currently run a mixed HT/2-ch system.  I have a Luxman integrated which lets me bypass (i.e. split) the preamp and let the Anthem AVP take over.  I won't let go of my Luxman for anything, so this is the complicated compromise I've done.  If I had an AVR, I'd do the same and eliminate my 3 extra amp channels.

My personal, preference is Mac, I like um. I don’t use all the latest and greatest when it comes to HT, I use a MX 120 and 121. I prefer the former though it’s not the best HT. I’ve found the play through on Mac let’s just about any HT/AV/whatever you want to call it, work VERY well with the added benefit of GREAT stereo sound through the MX120. The 121 is far better HT wise, but that 120 is a real jewel when it comes to stereo sound.

BTW, that’s not just "I like mac talk".. I have over 30 pieces of mac vintage and new, gear. The C2500 is a nice piece with a little work too, again most Macs have "play through" AND dual phono stage, some with MM and MC (with) gain selections.. Your current HT setup might be just fine. You want to improve the Stereo listening experience, the HT or BOTH?

What I'm suggesting is really the best of all worlds, FOR THE MONEY. 
If you look you can find a GREAT MX120 for under 2000.00 and still have great HT in another already owned piece.  I found a MX120 for 795.00 or something close with shipping and Mac shipping boxes too boot. Corner of the front glass had a crack.  In pics you had to really look.  I found the glass for 190.00 NEW. 

Just a though

Regards..

Is 2-channel or surround music important to you, or is this just home theater?  

Actually sorry to burst anyone's bubble but the best for the money home theater has been done, and its awesome. https://systems.audiogon.com/systems/8367

AVR or processor? The verdict is in: Neither.

OK MC, I gotta say, if your gonna keep tootin' the same horn you're gonna wear it out. You're gonna get carpal tunnel syndrome, at the least.
Swap tootin' hands, maybe it'll sound different. 

As for the best, come on now...It couldn't get any better if it already is?
So which is it, already the best or is there room for "getting better"?
Just askin'

I know it's lonely at the top, (God knows) but trust me you're not  ALL alone.  Let me move this 400 lb bohemi (that a female Bohemyth) into the launch position. I'm gonna turn it up down here in the Bay area.
Only one speaker because it knocks to many trees down on the way up.

Tell me how does "Girls just want to have fun" sounds" in Seattle.
So there, hows that for tootin'. That a definite HONK! ay?

I can turn it WAY UP up if you like.. Go for Anchorage. :-)

I feel a little James Brown comin' on. Get on up-a', (yea) Get on up now-a'  I'm a.............................................

Regards

The best AVP known to man at this time is from a French company named Trinnov. The Altitude 19 or Altitude 32 has no competition. Starts at 9k. Take your pick. 

Of course an upgrade to an av processor will be used for both ht and stereo.  An avp would join a b&w 803 d3, and b&w center htm2 d3 as fueled by a mc255 amp.  
So how much happier will this component family be if an avp joined the family (eg.  Arcam with dirac)? Seems an avp without Dirac these days could be problematic. Audyssey from marantz appears to be disappointing and troubling. 

I have two processors the Krell Showcase for movies and the Luxman CL38U SE for music. The difference between the two for music is night and day.

An AVR's amps are typically not very powerful (WPC specifications are usually for 1 or 2 channels driven, with a significant drop when multiple channels are driven), which means less dynamics and actual power to your speakers.

Technology is rapidly changing, so your AVR/preamp will become obsolete a lot faster than your amp.  Being able to keep a nice amp and upgrade just the processor section if there's some new feature you want/need is nice.  I think this is the 3rd processor I've used with my current 5 channel home theater amp.

To get the best of both worlds, consider an audio only preamp that has a home theater bypass option.  This setup can provide a much better two channel listening experience than using a home theater receiver or processor plus amp. 

Whether you have a receiver or separate amp home theater processor setup, there's a lot of crap packed into either one of those units, mostly cheap circuit boards and not much room for high quality parts.  Lots of compromise and a focus towards a kitchen sink of features, as opposed to a focus on sound quality.