[SSSN]

Specifically looking for something with a 3,5mm Microphone input.

 

[PurpleAngel]

  Specifically looking for something with a 3,5mm Microphone input.

 
Asus Xonar Essence STX & ST, Phoebus and the Creative SB-ZxR all come with a 10-Ohm headphone output impedance.
An Asus Xonar DX or D1 sound card (used is fine) with a FiiO E11K headphone amplifier makes a nice combo
The FiiO E11K has a less then 1-Ohm output impedance.
 
Xonar DX, used $54.
http://www.ebay.com/itm/121596141111?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 
FiiO E11K, $60
http://www.bhphotovideo.com/c/product/1073962-REG/fiio_fiio_e11k_portable_headphone.html

 

[ProtegeManiac]

http://us.creative.com/p/sound-blaster/sound-blaster-x7