Now you're using the poweramp part of AVR for music listening
For me, I won't krub as I believe NAD sounds better than Onkyo. Nevertheless, you can try as you may

it that way.
To me, why do I want to 'degrade' and 'contaminate' the music path with the inferior amplification path of AVR which has too many circuits that is more likely to interfere with music which demands the most direct path.
If it's me, I would sacrifice the sound quality of HT as I believe the focal point of HT is more on picture, not sound. You could try turn off the display, ie TV, projector, and turn on only the sound of the music/concert using AVR and see how long you could bear with it. Also, do the other way too. I believe you could bear more with the picture without sound alternative.
As such, I will hook whatever output from HT for left and right channel to int amp and left the rest with AVR. Then you need to fine tune/adjust the volume between HT and AVR to get a smooth sound level. Don't expect too much of sound quality from front two speakers with this method just make sure the level is OK. I believe it will be bearable as mostly you listen to center channel when you watched movies.
Let me know how it turns out.