In the Mac, you would open Audio/MIDI Setup (Audio view).

The "Finder" is the Mac icon (the face icon) denotes "Play alerts and sound effects through this device". I have sound output to the MONTAGE Driver.
The "Microphone" icon is the symbol for incoming audio signal "Use this device for sound input", I have set that to the MONTAGE Driver.
The "Speaker" icon is the symbol for outgoing audio signal. "Use this device for sound output", I have set that to the MONTAGE Driver
(The gear at the bottom left side of the dialog box, lets you select these options.)

On the INPUTS tab (shown above) you can see the various MONTAGE Outputs USB1-32 @44.1kHz

On the OUTPUTs tab (shown below) you can see the 6 audio returns from the computer to MONTAGE identified.

The 3rd and 4th RETURNS are identified as the "Digital L" and "Digital R", respectively.
Click on CONFIGURE SPEAKERS... to reveal where you can select them ...shown below:

Windows is similar. The outputs are not labeled like on Mac. See:

The problem is how, without a DAW or more advanced audio routing, it's difficult to tell Windows's applications to output sound to channels 3-6. By default, only channels 1&2 will have outputs even when you have the volume "pegged" in the balance section of the audio playback device settings (image above).

There's a quick way to rectify this -- which you may not "like" -- but it's quick and requires no software downloading or too fancy fiddling.

1) Press the windows key
2) Type "mono", for me this brings up an option/icon for "Audio Settings"
3) Click on the "Audio Settings" icon which brings up the "Audio" menu
4) Switch "Turn on mono audio" to "On".

This shoved audio into the Digital Inputs on Montage so I could record using the audio performance recorder.

Here's a picture:

Obviously, using this "mono" feature kills stereo separation. Ease of use doesn't come without some "minor" costs.

... and my thoughts on "wish the digital inputs were more flexible", in greater detail.

Right now, with these 6 channels of inputs to Montage from the PC (over USB) we have:

Channel 1 = Fixed to Main L
Channel 2 = Fixed to Main R
Channel 3 = Fixed to "Digital In" L - which is a digital version of the A/D input
Channel 4 = Fixed to "Digital In" R - "
Channel 5 = Fixed to Assign L
Channel 6 = Fixed to Assign R

Similar to how PARTs cannot be assigned a MIDI channel and that causes some configurations to get painted into a corner - the inability to route the 6 digital inputs sometimes creates the same situation. Since audio for "generic" use in Windows routes out Channels 1&2 (kind of like MIDI Channel 1 for some MIDI devices) -- what ends up happening is that Main L&R ends up being used for most digital USB and a certain class of users will not "fool" with the system to go any further than that. Although you could stand on one foot and hold your nose to "fix" this -- a more "friendly" approach would be to allow these digital channels to have a routing matrix on Montage, analogous to the type of routing matrix many would enjoy for the MIDI channel assignments to PARTs (on MIDI input).

One windows tip:

Versus using the "mono" mode in order to replicate the audio signal on digital Montage inputs 2-6, I found a better method which keeps Montage Digital Inputs Ch2/3 and Ch5/6 in stereo mode.

First, if you set windows to Mono mode, undo that first.

1) Download a free mixer application: https://www.vb-audio.com/Voicemeeter/index.htm
2) Install and reboot
3) Set "A1" (Right-hand side "HARDWARE OUT" ) to "MME: Line (Montage)"
4) Click "Stereo Repeat" under the "A MAIN OUT" section. For the outputs (far right) there are two sliders. The right-most is for virtual output. The next one over to the left is the Montage control which controls the level of the PC send to the Montage. Just to the left of this slider is the "Stereo Repeat" button you should click. When the button is light blue (ON), you will notice the "A MAIN OUT" bar graph has 6 bars moving assuming you have audio playing on your PC. I use this youtube link to check audio - since it streams 24/7: https://www.youtube.com/watch?v=2ccaHpy5Ewo

Once you click the "Stereo Repeat" you should now be able to use the performance recorder on Montage to record audio.

Note that this audio mixer is much deeper than what I've outlined. There is also support for routing MIDI over the net.

Also note that this mixer defaults audio to 16-bit 44.1kHz. If you want 24-bit, reconfigure (VoiceMeeter Input playback device properties under Windows "Sound/Playback" ).

Here's a picture of what you get:

Note you should be able to do something similar with a DAW. I installed this on a PC that I did not have a DAW installed -- so I didn't run through the equivalent steps of setting up Cubase, as an example, to accomplish the same thing. Cubase (without this mixer) will allow for you to do something similar - and with more control over the individual channels (Montage inputs 1-6).

I installed Voicemeeter and set it up the way you suggested. It didn’t work on my rig.

So I set it up a different way and got it to work. In the Windows 10 Sound Control Panel, I set Voicemeeter to be the default sound device. Then in Voicemeeter I set A1 to be the Yamaha USB ASIO driver. I was a little queasy about putting Voicemeeter between the Yamaha driver and my Montage, but everything seemed to work OK.

I have no idea why it works one way for you and another way for me. But at least it works. Thanks so much for pointing me in the direction of Voicemeeter.

Glad something worked. The main idea is to get the digital channels Ch3/Ch4 (Digital L & Digital R) to have audio sent there without requiring a DAW installed. VoiceMeeter was the only thing, thus far, I found to do this (in stereo). Windows alone can do this in Mono mode - but you lose spatial separation. And again, Cubase should be able to handle this with proper settings. My DAW machine is in transition, so I can't run through that. I personally would not use VoiceMeeter on a machine I had a DAW installed due to the extra software stage.

EDIT: I see what the difference is. I installed this on a machine with no Yamaha Steinberg USB driver installed. In this configuration, Montage will attach to Windows using standard drivers. Unlike the Yamaha Steinberg USB drivers - the standard drivers will install the "MONTAGE Line" device with 6 channels. The Yamaha Steinberg "MONTAGE Line" instance will only have two channels. The sound properties look different too.

In both cases, VoiceMeeter needs to be the default Audio Output device. When VoiceMeeter is installed - this is set by default (which is why I didn't call it out).

I've installed the Yamaha Steinberg USB driver and can confirm that selecting the ASIO driver as you've outlined is required to get the 6-channel output (from PC to Montage) to "engage" - and the rest of the instructions apply.

The reason I followed this is because I'd think a machine with a DAW would leverage the DAW for Audio routing -- and some random machine with youtube assumed no DAW installed - so I also assumed no Yamaha Steinberg USB drivers installed.

Very cool, I kinda discovered that playing youtube on the pc while connected to montage / speakers was very handy. When I saw this initial post, it seemed that recording the track seemed so close yet so far. Keeping for rainy day when I want to Jam with and record with the Tubes. How fun:p

Excellent!

The reason I followed this is because I'd think a machine with a DAW would leverage the DAW for Audio routing ...

I looked around a lot in Cubase Pro 9.5.21 and did not find any way to do what Voicemeeter does (direct a PC audio source to the Montage's Digital In bus).

I was surprised. I also had thought it would be possible in the DAW without Voicemeeter. Apparently that thought was incorrect.

Going the other way (publishing a stream to the web), I stumbled on some mixer app streaming on the xbox where some players and DAW artists where noodling and working with DAWs live. So I tried that using both Cubase and a standalong visualizer as a "game" to broadcast a stream. It works pretty much out of the box, but I did notice that one guy was streaming with super high fidelity, vs the ok lower fidelity my stream was generating. Not sure if putting that mixer in between would provide the full audio range.... another test for a rainy day. But its pretty cool to be able to jam live and stream without too much fuss.

I looked around a lot in Cubase Pro 9.5.21 and did not find any way to do what Voicemeeter does (direct a PC audio source to the Montage's Digital In bus).

I was surprised. I also had thought it would be possible in the DAW without Voicemeeter. Apparently that thought was incorrect.

You did not look hard enough, apparently.

In Cubase Pro 9.5
Go to STUDIO > Studio Setup > VST Audio System > Montage
Here you will see the 32 Inputs (yellow) and 6 Outputs (blue)

If you go to STUDIO > Audio Connections > click on the “Outputs” tab
Here you see the default Stereo Out is Audio Device = MONTAGE > Main L and Main R
Click on “Add Bus” > create 1 Stereo Bus
This will create “Stereo Out 2” assigned to the Montage’s “Digital L” and Digital R” returns

All you need do is select “Stereo Out 2” as the Output for the Audio you wish to send back to the MONTAGE’s internal mixer.

BM, that's not exactly going to solve the request. The problem isn't creating an output bus from Cubase to Montage's digital L/R inputs -- the issue is simultaneously feeding the computer noises (like Youtube or any other sound the computer makes) into the audio inputs of Cubase when only a single ASIO driver can be selected at a time in Windows. If the Yamaha Steinberg driver as an audio interface for the PC allowed to control audio output not only to Channels 1&2 (Main L/R) but also to any channel - then this would be solved. However, the use-Yamaha-Driver-as-a-PC-soundcard forces audio routing out Main L/R. On the Montage side - outside of using an analog loopback cable back to A/D in - there is no way to "re-route" the Main L/R digital input.

Cubase can play audio straight to Montage's digital L/R inputs (channels 2,3) - but the issue is getting the computer sounds into Cubase's stereo inputs.

It does appear that Voicemeeter (or something similar) - which makes up for lost control of the Yamaha Steinberg USB driver for PC-Soundcard audio routing - is required in order to get PC-Soundcard streams into Montage's Digital L/R.

The other option would be a little round-about. You could use something like ASIO4ALL to enable recording your soundcard (Realtek, or ...) audio in Cubase as an audio file. Then switch drivers to the Yamaha Steinberg USB ASIO driver to play what you just recorded back out - setting up your stereo out bus properly.

This all is part of what I've commented on in the past about lack of routing flexibility which does complicate things a bit. For now, Voicemeeter is the best option for doing this although I'd probably "not trust" having Voicemeeter in the audio chain unless I absolutely needed it for short bursts of targeted work.

You did not look hard enough, apparently.

In Cubase Pro 9.5
Go to STUDIO > Studio Setup > VST Audio System > Montage
Here you will see the 32 Inputs (yellow) and 6 Outputs (blue)

If you go to STUDIO > Audio Connections > click on the “Outputs” tab
Here you see the default Stereo Out is Audio Device = MONTAGE > Main L and Main R
Click on “Add Bus” > create 1 Stereo Bus
This will create “Stereo Out 2” assigned to the Montage’s “Digital L” and Digital R” returns

All you need do is select “Stereo Out 2” as the Output for the Audio you wish to send back to the MONTAGE’s internal mixer.

I already knew about those Cubase features. The images attached below show how I had them set up when I was trying to figure this out.

You might remember this thread, where I engaged in what one might think of as "stupid audio routing tricks" as part of learning about audio routing.

As part of trying to figure out how to get audio from things like YouTube videos into the Montage or Cubase, I did a lot of experimenting with those two windows. But nothing I tried worked. No matter what I did, the digital audio would enter the Montage on the Main bus instead of the Digital In bus. And that Main Bus only seems to go to Main L&R analog output.

As far as I can tell, the problem is that when a Windows PC is set to use the Yamaha USB ASIO Driver as its sound card, the digital audio is always directed to the Main bus on the Montage and there doesn't seem to be a way to direct that digital audio to the Digital In bus instead.

I could be wrong about this. I'd be happy to be wrong about this. Is there actually a way to "... select “Stereo Out 2” as the Output for the Audio you wish to send back to the MONTAGE’s internal mixer" so that digital audio coming out of a web browser gets directed to the Main digital input bus on the Montage?

There is no user-serviceable front-door way using the Yamaha Steinberg USB drivers as the soundcard (Windows 10 Audio Mixer default sound output) driver to direct audio to Montage's Digital L/R inputs unless possibly Windows mono mode is used (I haven't tested this with the Yamaha Steinberg USB driver - only the default generic) or certainly by using 3rd party hacks that add another streaming layer to your audio path.

Options (sticking with Windows) are to use 3rd party audio drivers or to use an analog loop-back from Main L/R outputs back to the A/D input. Maybe the mono mode trick if that works.

Or Yamaha could add the ability we’re talking about to the Windows driver. Apparently they did this on the Macintosh driver, and I don’t see why it would be impossible on Windows.

Can someone from Yamaha forward this (in my opinion) very reasonable request to the software engineers?

Just one more note: I searched extensively through the Windows Registry looking for something I could change to get the driver to do what I wanted it to. I didn’t find anything I could figure out.

It’s possible that someone at Yamaha could tell us what change to make in some registry key.