A consideration to keep your cost down, then be able to expand down the road if you desire would be the separate 2 channel Parasound ZPre3 preamp, which has HT pass through. As your Denon has the preouts necessary: ‘front’ preouts to the ZPre3 main input, then out to your amp. In pass though mode, the Denon will still use your amp for HT, just as you do now.
At that point, you could experiment with various DAC’s over time, connected to the Parasound ZPre3 for seperate 2 channel music bypassing the Denon entirely.
This would provide a lot of options moving forward.
I also have a combo HT and 2 channel setup in my living room, but all 2 channel is separate from the HT AVR completely. I had a Parasound Zpre in my main system, but now doing the same through my fairly new Belles Aria Signature preamp with HT pass through. A step-up no doubt, but my Parasound ZPre3 is now in my bedroom system, and don’t really want to sell it….a great little preamp.