How to use multiple audio devices as a surround?

First - there's a lot of questions asking how to playback audio stream through multiple devices, and this is not the goal of this project.

With that out of the way - the real goal is to use multiple different stereo or mono devices to make a "DIY" 5.1 or 7.1 surround. For example, I have my studio monitors, Bluetooth subwoofer, a pair of cheap speakers and pair of speakers built into my monitor. I want to use the SW as an SW (obviously), SMs as my right and left speaker, the cheap speakers as my rear left and right speaker and the monitor inbuilt speakers as a single-center speaker.

Also, my computer doesn't have enough jacks to do this, so SMs are connected to a studio audio interface, monitor speakers are over HDMI, woofer is Bluetooth as mentioned above and the rear s. are connected to the headphone jack.

1. You need all of those devices to support ASIO drivers. Most of mine don’t… So, a solution is program called ASIO4ALL, in which you can select devices to be converted to ASIO
2. You need to rout the sound somehow and for that I used ASIO Link Pro, which is now free!
   
   Essentially, you now have 4 virtual speakers created by Link Pro.
   1. You go to audio devices menu, right click on one of them and “configure”
   2. Set the desired number of speakers – I have done 5.1
   3. Set these as your default device
   4. Open ASIO Link and play something from Spotify of whatnot…
   5. In the menu, select “Init ASIO” A window should pop up with a bunch of tiles
   6. Back in that menu, click “Start ASIO” and a bunch more tiles should pop up in the big window.
   7. By clicking and dragging on them, you create virtual cables.
   8. Now you just must figure out which output channel is which
   9. Then stop the music, and connect the inputs to outputs in the order that you found in the previous step. Input channel mapping is as follows: Left, Right, Center, Sub, Rear Left, Rear Right, Side Left. Side Right. If you’re doing 5.1, than the last two don’t apply.
   10. Don’t forget to save your config! (Profile 1, load, save buttons)