[cheeno50]

I need a recommendation for an amp dac or sound card for my fidelio x2 headphones. Budget of 200-400$

It's mainly for computer use. What would give the biggest sound quality improvement and maybe some more bass punch?

 

[PurpleAngel]

I need a recommendation for an amp/dac or sound card for my Fidelio x2 headphones. Budget of 200-400$
It's mainly for computer use. What would give the biggest sound quality improvement and maybe some more bass punch?

 
Asus Xonar DX or D1 sound card (used $60) , used with an external headphone amplifier, should give you some good sound.
Are you looking for more detail in the audio or more musical sound?
 
Your Fidelio's need very little amplification (power), but an amplifier with a low output impedance would be helpful.
FiiO E11K, $60
Schiit Magni, $99
O2 (Objective 2), $130
 
If your not looking at doing much gaming or movie watch (headphone surround sound.
You could also get a ($99) Schiit Modi DAC (optical or USB) and use that with a separate headphone amplifier.
 
Unless you use an EQ or an amplifier with bass boost (E11K), you not going to get a lot more bass for your Fidelio X2.
Sometimes when trying too hard to increase bass, you end up with just louder bass with less detail.