Vincent Audio SV-500 Arriving Today

Considering that it's a hybrid amp, I'm surprised that you don't hear more of a difference, for better or worse. I guess give it a little time.

@jay73                                                                                                                                                                                                                 Some Amps can take a long time to run in, so as suggested give it some time.

Personally don't know your Denon, but appears it may be a good one.    

Of course there's always the question of System matching/synergy, Cables etc. to be considered.    

If it’s one thing I noticed from listening to Vincent amps is that they are very warm sounding. As I remember, the older Denon stuff is also voiced towards the warm side. So, even though the Vincent is a much better amplifier than what is in the Denon receiver, it is likely a very similar sonic signature. If you are looking for something with much more of a "wow" factor, the Vincent is probably not the right answer. Vincent will give you a very refined and smooth sound, but very warm sound as well (definitely laid back). It actually reminds me a lot of the older B&K amps (they were very warm sounding also).

If you decide the Vincent is not exciting enough for you, I am actually thinking the Yamaha integrateds are going to be too much on the "solid state" side. I would recommend you look at the Rotel RA-1592 integrated. In my opinion, it’s a much more refined sound than the Yamaha and it’s a lot more dynamic than the Vincent with more resolution. I am very impressed with the Rotel stuff for a budget level audiophile offering. It’s in the same price range as the Yamaha’s your looking at. With 200 watts per channel, it give significantly more power than the Yamaha/Vincent/Denon equipment. It has a pretty good DAC and also has a phono input (so you don’t have to use your Denon receiver for turntable duty).

Thanks for the suggestions everyone.
I am going to give as much time as possible but in order to make a decision, it will need to be within a couple of weeks since I have a 30 day window.
I am still learning the different terms like, "Warm Sounding" and what they mean and feel like.
But I think I am starting to get a little sense of it.
One thing that I am going to try to do this weekend is some critical listening.
I am going to pick some particular tracks across CD, Vinyl and DSD and then play them back through the Denon and Vincent.

I downloaded a random App to measure sound levels which I will use to make sure I am listening at approximately the same sound level through both units to try and keep things as fair as possible.
It's going to be a little bit of a hassle connecting/disconnecting speaker cables and what not between the 2 but there is no other way to do it.
I have considered the Yamaha IA's and also the Rotel. I had Rotel in my sights for some time also and heard a Demo at BestBuy of the RA-1572.

If I were to go with Rotel, it would probably be RA-1572.
The only problem with BestBuy's demo is, I can't get a real feel for the Rotel in their sound room.
Their amps go through some type of switchboard or unit and they can only play their own preselected music. You can't bring in your own CD or anything. I don't even know what format or quality their music is.

I highly suggest that you put something on that Vincent and leave it playing for 24 hours through its DAC to get a fair comparison.  
If you want to move away from that, I agree that the Rotel RA-1592 is a huge value and a nice sounding unit.  If you don't need the DAC,  I'd head for a Belles Aria Integrated.  It does have a nice phono section built in.