Sorry if this has been addressed before, but I couldn't find it after a few days of searching. I've worked out a way to individually select each of the 8 channels individually on a Mac, when outputting over HDMI. This is similar to the workaround in the sticky as it uses Soundflower (download here
). I used the latest version, which actually has support for 64 channel input and output.
This is pretty straightforward once you have Soundflower installed and running. You need to go to System Preferences ->Sound -> Output, and set this to Soundflower (64 ch).
Go to the MIDI controller via Applications -> Utilities ->Audio MIDI Setup, and select Soundflower (64 ch) as the output. In the image I’ve set the volume for channels 7 through 64 to zero, but it’s not necessary.
Next, open REW, and go to preferences. Set your output device as Default Device.
Now go to Applications -> Soundflower ->Soundflowerbed. This should load the application. It looks like an asterisk in your menu bar. When you click on that, you get a drop down. Mouse down and select HDMI under the Soundflower 64(ch) section. Now, click the asterisk again, and mouse down to the SoundFlower (64ch) and you get another set of options under routing. This is where the magic happens. Mouse over and set channels 2 through 64 to None. This deactivates each of those outputs. We only need one active at a time.
To begin with, I just ran a test tone from the REW generator to experiment. Go back to the Soundflowerbed icon and hover over Soundflower(64ch), mouse over to Channel 1, and you can select which output channel you want to route the sound to. For example, HDMI (1) corresponds to my L channel, HDMI (2) corresponds to my Center, and so on. I tried it with all 6 speakers in my living room setup.
The key here is to have only 1 channel activated at a time. The OS wants to send the sound to all 6 channels (or 8) at once, but Soundflower will let you turn all of them off (or on) individually.
Hope this is useful! This worked for me on a MacBook Pro running OS X 10.7.5. I'll be interested to know if it works for others.
input Configuration Update
I've noticed an intermittent issue where my UMM-6 is not recognized by REW. My Mac will immediately recognize it, and typically swaps the input in the system preferences to the UMM-6, but for some reason, REW does not see it despite all the other settings being correct. For now, the work-around has been to select the "Built-in Input" in REW. I'm not familiar with the other mics/sound cards, but this is how it's setup on my Mac.
Go to System Preferences -> Sound and make sure you click on the Input tab
Make sure your mic is selected (e.g. highlighted). You can also go to the MIDI controller via Applications -> Utilities ->Audio MIDI Setup and double check that your particular input device is active. Look for the microphone beside it.
Now open REW and go to the preferences. Select the Soundcard tab and under "Input Device and Input" you can select "Built-in input"
What's interesting about this is sometimes
REW will recognize my mic when "Default Device" is selected in REW, and sometimes
it won't. I haven't figured out why this is yet, but you have to make sure REW is not defaulting to your laptop/computer's built-in mic.