New high end processor

On paper, the AVM60 offers two advantages that may or may not matter to you: balanced outputs and a dedicated headphone amp. In reality the main advantage is the ability and flexibility to add better and or more powerful amplifier channels than those built into their receivers. 

The OP has mentioned that he has amplifiers sitting unused, waiting to be installed with a new prepro.  I'm not clear on whether those are new amps or old ones that he's had for years.  It sounds like there are several options being considered, 5.1 vs .7.1, atmos, avr vs separates.

If the amps are going to be employed, it goes without saying that there will need to be rack space and proper heat management for them.  As long as those needs can be met, I'd encourage a prepro, and you shouldn't need to spend anywhere near 5k.  Any model selected would be a MAJOR improvement over the currently being used Denon 3400.

The Marantz 7705 would provide everything needed and be thousands less.  They have the Audyssey room correction system, which is widely used and almost the industry standard.  Integra has Audyssey as well, where as the Yamaha model mentioned has their own room correction.  

All of these units have features, bells and whistles and connection options that may overwhelm.  No getting around that.  

Gonna pull the trigger on a 8805 from accessories4less. Question, as this is my 1st Pre pro and amp hookup, do I use balanced or un balanced cables?

Thanks

If your not going long distances, like over 10 feet, I would go un balanced RCA type. It will say you some money. Most people say you cant tell the difference on short runs .

By the way, when I contacted Accessories4less and enquired about the warranty on a refurbished 8805 he told me it was a factory warranty. He then told me that I could get a brand new one for $200 more by using code upgrade200. Pretty cool. $3400 delivered.