Switching from a sound card to external DAC/AMP

[Mich2k]

This will be my first post over on head-fi so I hope I'm doing it right.
 
So what I'd like to know is if I'll hear a difference going from a Asus Xonar D1 to a Schiit Magni (Or something else in that price range if its better). I'm currently using a pair of AKG Q701 headphones and love them but the Xonar D1 doesn't seem to amplify them as much as I'd like plus I've heard how sound cards tend to cut of some off the freq response.
 
Also, Bit off topic but would buying one of the expensive cables to replace the stock AKG cable improve the sound quality much? Thanks for your time in advance.

 

[PurpleAngel]

  This will be my first post over on head-fi so I hope I'm doing it right.
 
So what I'd like to know is if I'll hear a difference going from a Asus Xonar D1 to a Schiit Magni (Or something else in that price range if its better). I'm currently using a pair of AKG Q701 headphones and love them but the Xonar D1 doesn't seem to amplify them as much as I'd like plus I've heard how sound cards tend to cut of some off the freq response.
 
Also, Bit off topic but would buying one of the expensive cables to replace the stock AKG cable improve the sound quality much? Thanks for your time in advance.

The Xonar D1 is a good sound card with a nice CS4398 DAC chip, but it's front speaker line-output/headphone output is not really that great for driving headphones.
So get the Schiit Magni headphone amplifier ($99) and plug it into the Xonar D1 line-out/headphone jack and the Q701s into the Magni.

 

[Mich2k]

Awesome thank you for your help.