I have a Creative Sound Blaster X-Fi PCI card and Sony STR-DE685 amp.
I'm using 3.5mm to RCA cables to get left/right, rear left/rear right, and centre/sub. They are plugged from the sound card's 3.5mm jacks (in the correct slots) to the amp's RCA multi-channel in.
It is working correctly, the games have proper 5.1 surround, I haven't run into any compatibility issues, BUT my subwoofer refuses to work. In the playback devices interface, when testing my card, it plays sound through all speakers perfectly, including the sub. I cannot understand why the sub will work during testing and not in any game, and I've tested with old games like GTA SA to new games like Vampyr, even with YouTube on Firefox. I tried to uncheck the option that determines which speakers are full range, so that none but the sub would cover the bass range. No luck.
Observation from my side, when I swapped the centre and sub in channels on the amp, the centre speaker is able to play the test sound that is meant for, albeit without the bass. It may be a simple issue of the applications not opting to route the audio to the .1 sub channel. This doesn't quite make sense to me because the rest of the surround works perfectly....
Another observation is that if I, for example, plug the left out (card) into the sub in (amp), there is bass, again alluding to my suspicions above.
I have no idea where to go from here to get this working properly, it's infuriating. Perhaps I need some kind of auxiliary software? I don't know. Please help ?