Okay, I’ll try to help you out with this one. I’ve got my system at home set up for 5.1 output but it’s a little bit of setup that needs to be done to get it working.
First I’m not aware of any Audio interface (By this I mean a dedicated external box that hooks up via either usb or thunderbolt like a Universal audio Apollo twin solo or duo or a focusrite scarlet or steinberg ur22mkII or similar) that actually supports 5.1 inteface output out of the box. They’re all set up for monitor speakers which are just stereo. So if you can find an actual “audio interface” box that does support 5.1, let me know.
So we need to look at audio cards that actually have ASIO. don’t even try to screw around with asio4all in my opinion, get something that has ASIO support So I’m going to recommend what I have Creative Sound Blaster AE-7. It’s a PCIe card so you have to have a free card slot and have a PC. So there’s that.It’ll do 127 dB DNR hi-res 32-bit / 384 kHz playback via ESS SABRE-class 9018 DAC and DSD64 playback support and it comes with a fully certified ASIO driver.
Next, once you have your card installed, you need to hook up with the 3 audio cables (not the optical cable… the optical cable just doesn’t work well for me, but your mileage may vary) and make sure you calibrate your 5.1 surround sound with your speakers.
Once you’ve got that done, time to configure your cubase. by default it will start up in stereo mode. So you need to set up a 5.1 stereo configuration and map the outputs accordingly. How do you do this. Pretty simple. Launch cubase 11 , create an empty project,select a folder to put it into. Then in Cubase select “Studio”>“Adio connections”> click “outputs” tab and click “add bus” and from configurations click the dropdown and choose 5.1. then map the outputs for the device ports. You will need to disable the stereo bus to map all the outputs correctly.
The thing that you’ll also need to do is make sure you set up your instruments to make use of the 5.1 outputs. for example if you use Kontakt or Komplete Kontrol you need to set it up so that Kontakt will output to 5.1. To do that you go into Kontakt, load up your instrument (s) and right click below the primary output channel (which by default is 2 channels L/R and titled st1) you should get a new window that pops up saying channel name and audiochannels, click and scroll it up to 6 channels. 5 speakers and 1 subwoofer and then map the channels.
Then you need to go into the advanced setup menu for the instrument and go into instrument buses and add the surround panner. (if you need more details on this I can help but this is running afield of how to set up 5.1 in Cubase.) The point is, there are several steps here… The first is setting up the audio connection is first, then you map the outputs to the speakers, then you set up the virtual instuments to output to 5.1. Then you can add the instrument tracks to cubase and you should be good to go. The thing to remember though is that you need a fairly beefy audio card or audio interface that can do the processing needed to handle 3 times the number of audio outputs.
So SB AE5 or AE7 should be fine. Don’t waste time with the AE9 imo though