[Denon2010]

I have both the Xonar DG AND the ASUS Crystal Audio 2 onboard sound to me both sounds identical. I cannot tell the difference in a blind test except maybe the xonar DG is slightly brighter very slightly like 5% maybe.
 
Here is the thing years ago I had a Xonar DX which was much more expensive than the DG but no headphone amp and I can tell  you there was a different in clarity and smoothness in the DX but not a big deal maybe 15% difference.
 
Now I am 31 and I cannot tell the difference between 320k and FLAC
 
So I don't want to be conned by snake oil salesmen, I need to know if there is really going to be any kind of huge AUDIBLE benefit in changing the Xonar DG and if so to what? there is also ambient noise around me aswell cars passing etc
 
My headphone is Phillips SHP 9500 and Sennheiser HD 555

 

[PurpleAngel]

If I was looking to upgrade from the Xonar DG, for as little cost as possible.
I would get the Xonar DX (better DAC chip) sound card (used is fine) and a FiiO A3 (E11K) headphone amplifier.
Both the A3's >1-Ohm output impedance and stronger headphone amplifier (then the Xonar DG), might help in a little in the audio detail.
Also nice is the A3 can be powered of USB, or run off it's internal battery (portable amp).
 
Also install the Unified Xonar Drivers.
http://maxedtech.com/asus-xonar-unified-drivers/
 
Maybe leave the on-board audio disabled, in the BIOS.
 
If looking for a good closed headphone, for a good price, Soundmagic HP150 (closed) headphones.
Should give a nice boost in bass/treble, over the HD555.

 

[Denon2010]

  If I was looking to upgrade from the Xonar DG, for as little cost as possible.
I would get the Xonar DX (better DAC chip) sound card (used is fine) and a FiiO A3 (E11K) headphone amplifier.
Both the A3's >1-Ohm output impedance and stronger headphone amplifier (then the Xonar DG), might help in a little in the audio detail.
Also nice is the A3 can be powered of USB, or run off it's internal battery (portable amp).
 
Also install the Unified Xonar Drivers.
http://maxedtech.com/asus-xonar-unified-drivers/
 
Maybe leave the on-board audio disabled, in the BIOS.
 
If looking for a good closed headphone, for a good price, Soundmagic HP150 (closed) headphones.
Should give a nice boost in bass/treble, over the HD555.

 
Yeah Xonar DX is super expensive these days since they stopped making it.
 
Is this worth getting for $50 though? please keep in mind I have a SHP 9500 phillips and a HD 555 which are incredibly easy to drive and gave 0 improvement with the Xonar DG I learn now that "Headphone Amp" is just marketing gimmick. Every DAC has a headphone AMP to begin with. Just its a weak amp but how much different will this hybrid tube sound compared to my Xonar DG? is there any point in going for it for such easily driven headphones?
 
https://www.amazon.com/Nobsound%C2%AE-Vacuum-Integrated-Amplifier-Headphone/dp/B014FASL1A/ref=cm_cd_al_qh_dp_t

 

[PurpleAngel]

   
Yeah Xonar DX is super expensive these days since they stopped making it.
 
Is this worth getting for $50 though? please keep in mind I have a SHP 9500 phillips and a HD 555 which are incredibly easy to drive and gave 0 improvement with the Xonar DG I learn now that "Headphone Amp" is just marketing gimmick. Every DAC has a headphone AMP to begin with. Just its a weak amp but how much different will this hybrid tube sound compared to my Xonar DG? is there any point in going for it for such easily driven headphones?
 
https://www.amazon.com/Nobsound%C2%AE-Vacuum-Integrated-Amplifier-Headphone/dp/B014FASL1A/ref=cm_cd_al_qh_dp_t

I would be temped to get the Nobsound 6J9 and plug it into the Xonar DG or DX.
 
You also might consider selling off the SHP9500 and HD555 and get a (used) Soundmagic HP150 or (used) HP200 headphones and plug it into the Xonar DG.
At least that is what i would be considering.