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).