[GerGa]

I recently got a Fiio X5 2nd gen and I will be using it mostly in my car to play music via aux input.  I am looking for a new headunit.  What specs should I be paying attention to on the headunit.  Should I pay attention to aux input specs?
 
Aux input specs on a couple Kendwood headunits:
1st - KMM-BT312U
Frequency Response : 20Hz～20KHz ±3dB
Input Maximum Voltage : 1000mV
Input Impedance : 30KΩ
 
2nd - KDC-BT858U
Frequency Response : 20Hz - 20KHz ±3dB
Input Maximum Voltage : 1200mV
Input Impedance : 10KΩ
 
By the way the first is a "media receiver" with nocd player, the second has a cd player.
 
Will one match my X5 better than the other?  Not sure what the spec differences will mean.
I don't doubt the X5 2nd gen line out has enough power, though.
 
Thanks
 
PS. I am not using a receiver for it's usb storage capabilities because I prefer the file navigation, gapless playback of the X5.