Question How does one hook up 5.1 surround sound ? (Logitech Z607)

[deusman]

I may be stupid, but I think I am missing something obvious. I bought speakers Logitech Z607 for sole purpose of surround sound (never had that and this may be fine for start).
I have plan to attach it to PC.
Speakers have several outputs:

My motherboard is Gigabyte B450 AORUS M
It does have connections and all that, I connected them logically( sub/center to sub/center, rear to rear, front to side (and also tried line out)) , but seems only AUX inputs work anything from 5.1 is not working at all (I use 2xRCA to 3.5 mm cables) .

Windows tests only output left and right speaker (sub, center and rear is silent)
In regular audio it goes to left/right at best ignoring rear outputs (they still produce faint sound)
Switching to S/PDIF gives no sound
Changing 2.1 to 5.1 in speaker control panel changes nothing.

There are several reasons why I may be an idiot:

1. I need some kind of converted to make it work (decoder? )
2. I am missing some software
3. Speakers actually offer no surround sound to PC/ motherboard cant output it
4. Motherboard/speakers are defective
5. I dont know how to hook it up and/or I am blind.

Any help is much appreciated. I think in after-work hours my head is not working anymore...

 

[deusman]

I already use RCA to 3.5mm cables, connecting through Bluetooth is option, but that also reqires adapter. Not sure how good sound you can get through it though...
Still my motherboard have Realtek® ALC892 and it should have 5.1 channel audio... maybe it is only optical?