Hi Pete, as far as I know, no sound in DOS now a days, hasn't been since basically ISA days.
Does DosBox give you any other sound driver choices? If so, try them.
At least sound is now working for you, shame only on USB2, which is getting rare in computers. I know I only have USB3 on this box.
You could consider opening an issue with Arca Noae, sounds like their USB sound could be updated and who knows, perhaps USB3 could be fixed.
AN did fixes to USB isochronous audio with 12.16 (I am talking about USBXHCD.SYS). However, it seems that there is enough of a difference between for example Intel chipsets (and their USB 3.x support) and other chipsets (and their USB 3.x support) that sometimes isochronous audio (at least replay) works decently well for Intel but still won't work for those others.
Look here:
https://trac.netlabs.org/usb/ticket/96I don't think that this can be solved in USBAUDIO.SYS / USBAUD2.SYS. This is something that needs to be fixed in the USBXHCD.SYS as seemingly USB 2.x works ok (with the very same USB audio drivers). But I think USB audio has no priority for AN (an industry customer won't care for sure).
DOS box sound support: I have no clue of how audio gets passed over from DOS to the native OS/2 sound driver. It is possible that DOS will only ever use the very first sound device listed in MMPM2.INI (I am just guessing).
In that case, what you could do is change the sequence of devices in this section of MMPM2.INI:
[Drivers]
Digitalvideo=IBMDIGVIDPLAYER01,IBMMPEGPLAYER01
Speaker=SPEAKER
Headphone=HEADPHONE
Microphone=MICROPHONE
Filter=IBMFILTER01,IBMFILTER02,IBMFILTER03
Waveaudio=UNIAUDWAVE01,WMBWAVEUSB01,WMBWAVE2USB01
Ampmix=UNIAUDAMPMIX01,WMBAMPMIXUSB01,WMBAMPMIX2USB01
CDaudio=IBMCDAUDIO01,IBMCDAUDIO02
Sequencer=
What you could try is to change that to:
[Drivers]
Digitalvideo=IBMDIGVIDPLAYER01,IBMMPEGPLAYER01
Speaker=SPEAKER
Headphone=HEADPHONE
Microphone=MICROPHONE
Filter=IBMFILTER01,IBMFILTER02,IBMFILTER03
Waveaudio=WMBWAVEUSB01,UNIAUDWAVE01,WMBWAVE2USB01
Ampmix=WMBAMPMIXUSB01,UNIAUDAMPMIX01,WMBAMPMIX2USB01
CDaudio=IBMCDAUDIO01,IBMCDAUDIO02
Sequencer=
but as I said this is just guessing.