[HolyCheese]

The hd518 doesn't respond very well to amplification. But the DAC however is important.
I think the modi won't be a good match, I'm reading that alot of people have issues that it's too loud. I own a FiiO e10 and that doesn't have much room either. I think you'd be better off with the FiiO e10. Put your windows settings at 24 bits audio and set the volume at 50%. Then you have enough room.
 
Edit: Feel free to ask more questions.

 

[stevemk14ebr]

what does changing the bit do, and what about PCM rate
 

 

[HolyCheese]

If you digitally change the volume in 16 bit mode the sound quality will decrease. In 24 bit mode there is alot more room to change te volume. 
 
And I don't know what you mean with PCM rate.

 

[stv014]

Quote:

The hd518 doesn't respond very well to amplification. But the DAC however is important.
I think the modi won't be a good match, I'm reading that alot of people have issues that it's too loud. I own a FiiO e10 and that doesn't have much room either. I think you'd be better off with the FiiO e10.

 
The FiiO E10 actually has a technically worse (but still not bad) DAC than the Xonar DX, and also less features. If the card is performing optimally, the Modi is not really worth getting either.
For the HD5xx, amplification can in fact make a difference, because these headphones are quite sensitive to the output impedance of the amplifier.

 

[stevemk14ebr]

on my sound card i have the option to change the sample rate to say PCM 192 KHz to PCM 44.1 KHz
 

 

[HolyCheese]

I think you should leave that at automatic if possible, otherwise set it as the highest as your soundcard can support.

 

[stevemk14ebr]

there is no automatic so i set it to 192