I am of the same knowledge 
My interest in your problem was because I am trying to solve another “simple appliance” which isn’t behaving since the Turris arrived…
I too have a Yamaha RX-V1073 and I have just tried the net radio out on it. It works OK, I was able to load the station list and then stream BBC Radio 2.
I would note, I am not using Knot but dnsmasq as the DNS, I followed the instructions in this thread:
I also changed /etc/config/resolver as follows to change the port to not conflict with dnsmasq and run Unbound:
option port ‘53’ to option port ‘153’
option prefered_resolver ‘kresd’ to option prefered_resolver ‘unbound’
Here’s the pcap of all the data from turning on, then eventually streaming the radio station:
https://transfer.sh/Y6yLo/yamaha161118a.pcapng
Hope that helps?