[abcd]

A FIIO E7.
 
 
[size=small]Sorry I want to get another amp and some hd 600's, but I'm not sure if this will be good with my onboard sound. Should I get an Asus Xonar DG?[/size]

 

[NA Blur]

I think both the HD-600 and more expensive and better sounding HD-650 will not be well driven by your current system.  That said you may want to consider other headphones.  This would be both a less expensive option and you could prevent upgrading your current gear and just upgrade your headphones.
 
What music do you listen to most of the time?
 
Do you need a portable headphone?
 
Is on-ear or over the ear style headphone preferred?
 
Would you like a headphone with a little extra bass?
 
What is your budget?
 
Answer those questions and you will get far better responses from the head-fi community.
 
Personally I went for the HD-650 years ago.  I ended up not liking the sound because the veil is just too much for most of my music or I had to have the volume up too high to get the sound I wanted.  There are many of us who have tried hundreds of headphones who have purchased the HD-600 / HD-650 and in the end did not like them.  I say this not to discourage you, but I am trying to prevent you from going down the road that so many of us have ending up with an expensive and not to our liking headphone.
 
I would suggest looking into the following headphones:
 
1.)  Audio Technica ATH-M50
2.)  Sennheiser HD 25-1-ii
3.)  byerdynamic DT880 ( 32 Ohm version )
4.)  Denon AH-D2000
5.)  AKG K550
 
All of those I have listened to and prefer over the HD-600 / 650.  I think that you will enjoy those in the long run more than the 600 or 650.

 

[PurpleAngel]

Quote:

A FIIO E7.
[size=small]Sorry I want to get another amp and some HD600's, but I'm not sure if this will be good with my on-board sound. Should I get an Asus Xonar DG?[/size]

Do you own the E7 or just thinking of getting it?
 
The Asus Xonar DG (& DGX) would be good (with the E9) if you were looking for 5.1 surround sound, the Xonar DX (& D1) has a better DAC then the DG(X) and comes with 7.1 surround sound.
The Fiio E7 would be good if you do not need surround sound and want to have a portable headphone amplifier.
You really can use the E9 with the Xonar or the E7, but you can't use the Xonar and the E7 together at the same time, with the E9.