Hi Bit,
The R7-260x video card won't increase (or negatively affect) audio performance.
They're active cooled... but some units are much more quiet than others.
We offer the R7-260x as an option for clients looking to run three monitors... while also providing some hardware acceleration for video editing apps (Vegas Pro, Premier Pro, After-Effects, etc).
For straight-up audio production:
If you're not doing any video editing, a HD5450 (passive cooled) is perfect...
Onboard HD4600 graphics consumes a small amount of system RAM but also works fine