Separate Amp for AV receiver

What is the amp?  I mean if it is an old Krell or Bryston that the OP is calling cheap, it might make a difference.  The ultimate question here is the separation of pre amp and power amp.  For the sake of argument let’s say we are in the 2 channel world.  Someone has a cheap pre and a super duper power power amp.  Now in theory all that the pre is supposed to do is pass the signal unchanged from the source to the power amp, and the character of the latter will determine the sound.  In practice, we know that the pre matters very much, and most of us budget roughly equivalent for pre and pro.
  I would argue that the pre is even more important in multichannel, because the challenge of reproducing a realistic—as opposed to gimmicky—soundstage in multichannel.  So to cut to the OP specific question, and having actually owned that Denon for a brief time, I wouldn’t bother.  It will be the lipstick on the pig phenomenon.  The Denon is dry, desiccated, and it could be exhibit A in support of Millercarbon’s post.  No power amp will fix what is wrong with it.
  I disagree with MC in that while separates are to be preferred, it is possible to get pretty good sound from a receiver.  Good room correction helps, and again I think RC is more important in multichannel because some of those surround speakers can blow up a soundstage unless they are properly controlled 

@millercarbon summarized it succinctly …. Point, set, and match in tennis match jargon.

Everything in this hobby is built to its price point, without prejudice to AVR’s suffering material audio compromises as primarily video gear with everything complimentary being stuffed into a limited space unibox. . The mass-market AVR’s have limited power supplies as a major culprit.

The DENON AVR-X4300H is (was - now discontinued…) only an upper-mid range AVR with an RRP of $2,999. It was never designed nor built to perform at Hi-Fi strata audio performance .

I concur with all the prior posts that AVR’s comparatively suffer in audio performance. Adding an external power amp now still won’t compensate for its inherent design and build limitations.

 I agree, separates are the way, I guess when I purchased this about five years ago I was hoping it would perform as well as my old Yamaha A1. Not even close. I'll start looking into a new AV system. What do you think about Emotiva?

I'm looking at my avr-x4300H right now and it gets the job done for movie sound.  !  . Only !! 

Oh nuts you got MC going again.
You'd better buy a Raven before his lid flips.

On another note the only legitimate surround sound is 4.0 or 5.1.
On up is gimmicks to sell crap to dummies.
Most movies and music is not mixed above 5.1.