Originally Posted by cib24
When you say 10 ohms is the lowest, does that include sound cards without an amp? Because if all sound cards and motherboards have a 10 ohms impedance level then how does buying a Xonar DX and using an amp with it make any difference? What kind of math is involved in determining how an external amp responds when connected to a sound card if it has a higher impedance than the amp?
Most current sound cards (and all older ones) have a higher then 10-Ohm output impedance, like 35-Ohm, 47-Ohm, 75-Ohm or 100-Ohm.
The Essence STX & ST (Asus Phoebus) are some of the few sound cards with a 10-Ohm impedance, I know there are a few others, but I do not know for sure which models.
(chances are the sound cards with the built in amp. have the low impedance)
All non-amped sound cards (& motherboards) are going to have a higher impedance.
When you plug a external headphone amplifier into the Xonar DX (or any non-amped sound card), the sound card's impedance no longer count's. just the external amplifier's impedance.
A normal "line-out" jack (like RCAs) is going to have a high impedance, which is normal.
I guess you could say non-amped sound cards use a 3.5mm line-out jack (green) that pretends to be a headphone jack.
Edited by PurpleAngel - 12/13/12 at 5:22pm