What headphones are you using for music and gaming ?
How loud do you want to play ?
For surround sound gaming I assume you want to use a normal (2 driver) headphone and plan to use virtual surround ?
I think any soundcard (+ software) that can be used for gaming also will work fine for hifi when all the bells and whistles are switched off. Whether you need an external amp or not depends on the questions asked above.
use your EARS to enjoy MUSIC .... NOT as an analyzer
This is long shot but AMD has TrueAudio technology. Software can use GPU power to calculate all the effects to the sound in real tinme. You need only a basic sound card / DAC. There is two big downsides. You need an AMD graphic card and a game that support it and there few games that support it. Games that support TrueAudio: Murdered Soul Suspect (consoles only), Star Sitizen, Thief and Lichdom: Battlemage. Star Sitizen is going to be big on audio side. Worth the wait. And TrueAudio Next is now integrated to Steam. We have to now wait for games