Audio Drivers/ Mobo Not Working - help!

Please, can someone help as I'm pulling my hair out!

I recently built my first PC on the Asrock Fatal1ty B450 Gaming-ITX/ac motherboard & Ryzen (3 2200G) with a clean install of Win 10 Pro (OEM version) etc. It's purred ever since I fired it all up and my Bluetooth headphones have worked like a charm since I first tried them (and still do).

However, I recently got some Creative Pebble Plus speakers as part of the finishing touches to my set up but cannot for the life in me get any sound through them from the PC. I've checked everything I can think of:

- the wire from the speakers is plugged into the lime coloured port on the rear panel (according to the mobo manual)
- nothing is muted
- default device is set properly
- checked speakers work (using my mobile)
- checked headphones work on mobile (they do) but these also get nothing when wired into the PC
- checked BIOS has audio enabled (I think it was under 'south bridge configuration' - over my head, but I followed a post and have double checked)

Then, I realised that the audio driver was a Microsoft one. Thinking I'd cracked it, I then installed the appropriate Realtek audio driver from the specific Asrock motherboard download page for my specific mobo, but... nothing.

The rear panel port is not fried because when I plug the speakers it makes a short static noise for a moment (as speakers tend to when being plugged in) and in the Realtek Audio Control app it lights up the lime port (and goes out when I remove). Also, when music is playing (on say YouTube or Google Play etc) the little green equalizer in 'Manage audio devices' (Win 10) shows up so it seems the issue is purely around the driver/ mobo connecting the sounds to the speakers?

I am at an absolute loss after spending two days trying out different drivers (being honest, it took me until this morning to actually locate the driver on the Asrock mobo page!), going round in circles doing the above list over and over, restart after restart but nothing seems to work... I've read countless posts on here and other places about issues with Realtek drivers etc but only a couple were exactly like my issue (albeit on different mobos), but the solutions they found don't seem to apply (rolling back driver update & somehow not using the Sound Blaster Cinema 5 crap this mobo comes with - no idea what this even means tbh).

Any help would be seriously appreciated - anyone else suffering from a similar issue?

Thanks
Gav