Any need for a sound card?

[willhub]

I have a Z5500 system connected up via optical, everything else via HDMi, any need to get a sound card?? I just see them in smart looking boxes with heatsinks looking like some swanky bit of electrical that I possibly need, what's the benefit?

 

[EsaT]

When using digital connections there's no signal quality differences between any kind sound cards:
D/A converters of those aren't used and neither there can be interference from bad design of analog signal chain.

Though if it's headphones in end of sound reproduction chain then binaural sound simulation is major gaming immersion improvement for good headphones.