Move From AVR to Integrated?

Marantz pm7000n is a true all-in-one with a built in streamer ready made for Tidal, Qobuz, etc., for $999 USD, as another option if you want an all in one box without having to get a separate streamer with the Outlaw. I own one and can strongly recommend. Replaced my Bluesound Powernode2 in my office system, and much better. One of the Brit hifi mags declared it the best all-in-one under $1k, but I forget which. Just check the reviews, very highly acclaimed.

Last month I bought the Andover Songbird as I was searching for an affordable way to stream free internet radio from a browser on my Windows pc to my older stereo system via WiFi.  I did not want to use a streaming service such as Spotify or Tidal. It seemed easy.  I connected the Songbird to an aux input of the preamp, and, as indicated by the manual, a female voice announced its presence through my speakers.  It also appears as a device on my network.  I had no difficulty streaming from my iPhone but have not succeeded in getting any sound from the pc.  According to the "manual," the songbird should appear on pc's sound control panel.  It does not.  Two phone calls and an email to Andover support have not produced any response.  I would be interested to learn if anyone else has succeeded where I have not. 

I think I’ve decided on budgeting a few more bucks and going this route:

1. miniDSP SHD - DAC, Dirac Live processor for well reviewed sub integration, crossovers, parametric EQ, streamer, balanced and RCA inputs and outputs. Promising high signal to noise measurements.
2. Monoprice Monolith 2x200 AB amp. - made by ATI with really solid measurements that should be a piece to last years and power anything I need.

Comes to about 2200. This is more than the 1500 budget, but it’s what I’m shooting for.

The best solution for you would be to add a 2ch amp and use your receiver as the preamp.  I just did this with my Yamaha RX-A1000. Fortunately your Denon has HDMI ARC, a 12v trigger, and pre-outs for the mains which is all you need.  I really wanted to keep a single remote and have everything turn on and off with a single button which is where ARC and the 12v trigger come in handy. There are hundreds of 2ch amps you can find in your price range.  It won’t be hard to significantly improve upon the amp section of your Denon. 
I was limited on space so I went with a Linn AV5105, which is an incredible used bargain in the 400-500 dollar range. They were originally around $1800-1900 new.  

@perkadin My Denon does not have pre outs, unfortunately. Only the 3xxx series and up does. The cost of buying a new AVR and an amp would be just as much as something more dedicated like the SHD which has better DAC, better room correction, high signal to noise, etc..