I'd like to give this a go, but the Signalyst site has no explanation about how to set anything up. I haven't even worked out how to remove items from the playlist in HQPlayer! That it started up with the volume at zero, leading me to a massive run-around trying to work out why I didn't have sound doesn't encourage me.
The post from @iamoneagain is helpful. There is also this post on the Roon Community forum which walks you through setting up HQ Player with Roon:
HQ Player's user experience is a horror-show, so I would recommend only using it with Roon. The link above shows how to set that up (it's pretty straight-forward).