Redirect USB audio output to the speaker | Guitar link interface

If I connect my guitar directly to the line in and use Guitar Rig 5 with ASIO, it'll use the Speakers (Realtek HD Audio) output device exclusively, meaning that I won't be able to play sounds from any other app through that output device (it didn't use to be like that for Windows XP).

For this very reason I've bought a USB guitar link interface which gives me another output device that I could use only for playing guitar. My goal is to somehow redirect the output of that device to my speakers. Stereo mix is not picking up the sound from the USB device, only my Speakers (Realtek HD).

How could I get the sound from that to my speakers so that I can play music and my guitar at the same time?

See the playback devices

And recording devices with stereo mix settings

A software mixer like Voicemeeter allows you to set Guitar Rig 5 to output to a software AUX controlled by the mixer, then you can have the mixer mix the system audio with the Guitar Rig 5 output to your real audio output.