If you're literally virtually patching your sound card's output into line 1's input well, you may not be in luck, because whether or not NVDA is on line 1 won't matter since it's the output that's going over. You could use a second sound card if you had one. I think another way would be to set line 1 in the playback tab of mmsys.cpl as the default device, which would send all your sound there, but if you wanted microphone, you'd have to use a repeater.

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I'm not the greatest at getting VAC to always do what I want, but the question I'd be asking myself is what do I want to do. If your answer is record a specific app, I'd do it slightly differently. If your app has pipable output i.e. you can choose where to send it, you can simply pipe it to line 1, and then your recorder of choice can be receiving from line line 1 input. If your app doesn't have pipable output, well, Windows 10 can now redirect sound on a per-app basis to an output of your choosing. Windows I >> system >> sound, then tab to "App volume and device preferences". Once in there, you search for the list, find the app (note that it must have played sound at least once), then tab to output which is a combobox you can manipulate. The thing is a bit finicky, like it will throw you out of the tab order sometimes, but you can get back in, it's definitely workable.. Once the app is redirected, you then can fire up your editor or DAW and record. If you need your mic to be patched in, and you can deal with the hearing of yourself, a hackish way is to go to the microphone tab in mmsys.cpl, then hit listen to this device, which is a checkbox, the combo box after it tells Windows where to pipe the output, in this case, line 1. hth