[Shini44]

So i have asus Xonar Phoebus sound card and i am planing to buy senhisier HD 595 and IE80

would i need to use an amplifier for a higher quality?

 

[fabio-fi]

Both are easy to drive headphones, and the Xonar phoebus come with a built in headphone amp. I dont think its necessary. 

 

[PurpleAngel]

The Phoebus comes with a headphone amplifier rated up to 600-Ohm, so it fine with the HD595.
But the Phoebus headphone jack comes with a 10-Ohm impedance (resistance, measured in Ohms)
It's preferred to have the impedance of the headphone be 8 times or more then the impedance of your amplifier/headphone jack.
The Senn IE80s are only 16-Ohm, so may not sound the best connected to the Phoebus's headphone jack.