The SC-55 is connected to a 2019 iMac via a Roland UM-ONE Mk2 USB MIDI adapter. The drivers installed fine and I tested the functionality via the Audio MIDI Setup app in macOS. In ScummVM I selected the UM-ONE as the music driver. I should add that I normally have external Bose speakers plugged into the single audio-out jack on the iMac. To test the SC-55 I instead plugged the speakers into the audio-out jack on the front of the module, as shown below.
With this configuration, when I start a game in ScummVM, the SC-55 works as expected and I hear the music through the Bose speakers, but I hear no digital voice or sound effects (I am using King's Quest VI and VII for testing purposes). I thought the digital sounds would play through the iMac's internal speakers, but there is just silence.
I then plugged the speakers back into the iMac, but left the SC-55 on. This time, when I start ScummVM I hear the digital voice and sound effects through the internal iMac speakers. To hear the SC-55 music I had to plug in some external earphones, and I can hear it is definitely playing the music through those.
Now, the strange thing is that after starting up with the Bose speakers plugged into the iMac, if I remove them during gameplay and plug them into the front of the SC-55, I can then hear music through my Bose speakers and the digital voice and sound effects through my iMac's internal speakers.
My questions are:
1. Why does ScummVM fail to play digital audio when the SC-55 is plugged into the speakers, unless I start with the external speakers plugged into the Mac and then hot-swap them back to the SC-55 during gameplay?
2. Since the iMac only has one audio-out jack and no line-in, should I be looking at some kind of external adapter or sound card that will augment my Mac's audio capability? Could the RCA jacks on the SC-55 be of any use in this way?
Ideally, I want to have the music from the SC-55 and the digital sound effects from the iMac played together via the external Bose speakers.
I realize some of these issues have nothing to do with ScummVM, but I am reaching out for help because there is scant information on the Internet regarding these issues on Macs, and I am not really an audiophile.
