They use the majority of the same parts. But the Phoebus is made for gaming, and so adds bass and effects, whilst the STX produces the intended sound perfectly.
The Phoebus is more made for headsets, and so doesn't perform well in things like music and films - in fact, in those it's not great at all.
The STX on the other hand is made for listening to/creating music primarily. So it reproduces the sounds pretty much perfectly - and has also been designed for use with headphones, not headsets like the Phoebus.
You can add effects with the STX to make is more bass heavy, and sound exactly like the Phoebus - but you can't make the Phoebus sound like the STX, making it pretty redundant against it.
If the OP is ONLY using it for gaming with a headset, then he probably wouldn't notice too much difference between the two. But as he's also using it for music with proper headphones too, the STX is always going to be the better option.
This may all be pretty irrelevant however as the OP hasn't given us a budget, and we're talking about the two most expensive cards on the market :lol:
