Hi, sorry for the late answer. No I not on a VM, this is a native Ubuntu installation. :)
I’ve spoken to the Visionaire developers about this and they have said that a new audio system is in production, but won’t be available until next year, unfortunately!
Sorry, it looks like I won’t be able to provide a version with perfect audio which is compatible with your system set up in the near future! In the meantime, if you would like a refund for your purchase, I think you can contact Itch.io support. 😊
I've looked for such options in the Pulse Audio volume controls but I haven't found it. I can only select there HDMI-Devices and the internal speakers of my notebook (Dell Alienware) but as I don't habe any HDMI device connected I use the settings for the internal speakers. But I will see if I can find something later. :)
But I found something else interesting. I have connected my Fiio Q1 Mark II (FQ1222) DAC via USB to my Notebook and used this as the sound card. Now the sound is perfect! This would be a good solution for me but I think it would be interesting for the developers what's causing this problem. If I can do anything to help you, please let me know.