Hello TLF,
Thank you for trying AROS and providing extensive feedback
Please keep in mind that i do not have experience with either VBox on MacOS or any recent VBox. Last time i've tried would be around the late 4 series on a Windows host. Your mileage may vary on MacOS.
The information is a bit scattered around in the manual and i am therefor not entirely sure if you are just being thorough or maybe the information provides contradicting e.g. confusing information for you.
So i'm perhaps stating the obvious. Sorry in case i am.
Qemu, VMWare and VBox are all software that are able to provide a virtualized environment where you are able to install AROS but the information that is listed is not interchangeable. Meaning that if Qemu lists SB128 as supported in AROS that this does not automatically mean AROS also supports the same audio hardware for VMWare, VirtualBox and/or real SoundBlaster (native) hardware (or vice verse).
The last time i checked and so afaik only the AC'97 audio emulation of VBox is (fully) supported by AROS. And even then sometimes things can go wrong. User Neil reported on the old forums that f.e. AC97 audio was broken in VirtualBox 5.1.8 (which was not AROS at fault but VirtualBox that did seem to have broken things for that release).
I'm not sure if I just need to configure a bit differently or if my hardware is inappropriate. Any guidance is much appreciated! (is it possible there is just a separate volume control that I need to increase elsewhere for the system?)
My first incling would be to say no but i am aware that paolone is experimenting with a global volume knob/slider setting. Not sure if that made it into Icaros Desktop 2.2.6
Under normal circumstances the only place where to set the audio volume is when selecting the dropdown music units manually each at a time and setting the audio level for each unit (and for all untis). Of course a save settings is also required. It is probaby best to do a reboot of the AROS VM as well after you have saved your settings.
In case you are experimenting with your virtual machine's audi settings (and also network settings) then make sure to always do a 'cold' reboot of AROS (just close down the VM where AROS is installed and restart) each time you tweak the audio settings and/or audio driver in order to make sure there is not some interferences with old setttings. AROS kind of dislikes the 'warm' reboot in such cases.
In case you are still not able to get things working then it would perhaps be an idea to turn on some debugging. fwiw and afaik user ncaffferkey is the person that knows about and is able to share about AROS' audio. But he also seems rather busy lately. No idea where the other devs are atm or if someone else is around with more information about the topic.