Maybe there's a different way - but if the sound is coming out Main L&R, I'd "loop back" a physical cable from Main L&R back to the A/D inputs and then use A/D inputs for the recording.

I've "wished" the USB digital inputs (TO Montage) would be more flexible in the routing. Maybe they are.

https://www.yamahasynth.com/forum/22958-montage-usb-digital-input-as-modulation-source-for-vocoder
https://www.yamahasynth.com/forum/13811-deleted-113

Take the headphone output of your iPad and connect it to the A/D Input - treat it as a Line In. Fortunately Apple left the standard 1/8" mini stereo jack on the iPads.
This will allow the signal to enter via "A/D In" in the Signal Flow diagram above.

A stereo mini 1/8" to two 1/4" adapter works well. The analog circuitry is very good in MONTAGE.
As an A/D In that signal can now be processed in the MONTAGE.

Considering PC, as in original post, is not an iPad - possibly purchase one of those first.

Oh, a PC! Don’t know why I assumed a tablet for Internet connectivity... To play audio on your computer through MONTAGE, you don’t need anything special, you can play audio in YouTube, for example, or any other computer utility program and, through routing... record that to Cubase. Simply route the computer’s general Sound functions (including YouTube audio) to the MONTAGE using the “Digital L,R” - it will show up on the current MONTAGE Performance as “Digital In”

I don’t have a Windows Computer here but you can select the MONTAGE as your general audio interface so programs like YouTube and Media Player Output Signal to the MONTAGE’s second pair of Inputs (3rd and 4th Inputs) “Digital In L/R”

I’ve not done it but should be possible without running the Analog Out to the A/D Input (avoid that).
With programs like Cubase, the setup is done locally, within the program. Those that use the Window built-in Sound Driver are selected under CONTROL PANEL > Hardware and Sound > Sound

There is usually a way to route the computer audio so it uses the MONTAGE “Digital In”. Let us know if you need more specific help.

I just tried to set this up but I couldn’t figure out how. I have 3-Montage set up as my default sound device on my Windows 10 PC.

What is “Digital L, R?” I don’t see that anywhere on my PC.

When I play music with the PC, it comes out of the speakers attached to my Montage. But when I look at the Audio Mixing, the meter for “Digi” doesn’t show any activity at all, even though I can hear the music playing.

I definitely need more specific help.

I tried turning “Exclusive Mode” on and off on the PC sound settings for the Montage, but it didn’t help.

I mentioned that ...”those [programs] that use the Window built-in Sound Driver are selected under CONTROL PANEL > Hardware and Sound > Sound
Know this you are re-routing all computer sound to the MONTAGE as a replacement for you computer’s built-in soundcard.

This is where in a Windows computer (that has the “Yamaha Steinberg USB Driver” installed) your MONTAGE can be selected for your “Playback” and “Recording” device.

When you click one of the options you will see it define the number of returns it sees... it should see the properties of MONTAGE as a six returns.
The first pair feed the MONTAGE “Main L/R”
The next pair feed the MONTAGE “Digital In”
The last pair feed the MONTAGE “Asgn L/R”

Take these screenshots:
Go to CONTROL PANEL > click on “Hardware and Sound” > click on “Yamaha Steinberg USB Driver” > take screen shot

Go to CONTROL PANEL > click on “SOUND” > click on the “Playback” tab: screenshot, click on “Recording” tab: screenshot

You should be able to select and configure the MONTAGE as the device for all computer sound duties (forgive me for not being as Windows step-by-step savvy, it’s been awhile...) but if memory serves this should get you in the ballpark, if not all the way down front to the good seats... let us know

Thanks..

Here are the screenshots:

When you click one of the options you will see it define the number of returns it sees... it should see the properties of MONTAGE as a six returns.
The first pair feed the MONTAGE “Main L/R”
The next pair feed the MONTAGE “Digital In”
The last pair feed the MONTAGE “Asgn L/R”

As you will see from the screenshots, I don’t see that side of alternatives.

I tried to make the screenshots inline, but it didn’t work. The links do work, though.

“Side of” —> “set of”

Siri is not that good at voice recognition.

Use your mouse and highlight the “MONTAGE” option, in both the “Playback” and “Recording” tabs. Then the greyed out options, for “Configure”, “Properties”, etc., will appear. Then click on those options and configure your computer’s sound... let us know... you’re very close, just follow your Windows instincts .

Under one of those options you’ll see three pairs of MONTAGE options, if they are identified by name, you want “Digital L/R” if identified by numbers, you want the 3rd and 4th...

"...just follow your Windows instincts" I love that one 😀

https://youtu.be/zR7CeC-rqiE

Use your mouse and highlight the “MONTAGE” option, in both the “Playback” and “Recording” tabs. Then the greyed out options, for “Configure”, “Properties”, etc., will appear. Then click on those options and configure your computer’s sound... let us know... you’re very close, just follow your Windows instincts .

Under one of those options you’ll see three pairs of MONTAGE options, if they are identified by name, you want “Digital L/R” if identified by numbers, you want the 3rd and 4th...

I tried what you suggested, but didn’t manage to find what you described.

I started here:

Clicking on “Properties” got me here:

Clicking on “Properties” got me here:

Clicking “Change Settings” got me here:

I also tried going in through the Device Manager, but I got to the same dead end.

Is it possible that it might require editing a registry key?