Originally Posted by FeralFox
Hi. I have always had the Xonar connected to the power supply through the 4 pin.
I will try disabling Realtek drivers.
(Have now tried this. It did nothing to the volume.)
I have been plugging my headphones into the Xonar card itself. Not into a header.
When I say the headphones are louder through the motherboard. I mean I am plugging them into the green speaker port on the back of my motherboard, which is a z87 gigabyte ud3h if it makes a difference. I also heard that the ad700 was not very sensitive to ampin . And that at shouldn't really distort the sound, but it shouldn't be quieter than motherboard should it?
The impedance issue is not really the same as amplifying.
Very basically, I guess you could say impedance is how well the power is handled, where as amplification is basically how much power is added.
True the Audio Technica ATH-AD700 do not need a lot of power an usually sound good no matter what they are plugged into.
(I own the ATH-AD700, ATH-A900X, ATH-W1000X).
I suspect the Gigabyte Z87 UD4H's built in audio hardware is better at driving headphones then the Xonar DX.
Where as the Xonar DX's CS4398 DAC chip provides better audio quality then the Z87 UD3H on-board (built in) audio.
My Yamaha receiver's headphone output jack has a lot of power (more then your motherboard's audio), but because of the Yamaha's high impedance, I can plug my A900X's into the receiver, but no matter how high I turn up the volume knob, the A900Xs never gets loud.
With 32-Ohm headphones like the AD700s, a headphone amplifier with an output impedance of 4-Ohms or less would be recommended, the Xonar DX's output impedance is 100-Ohms.
Where your Gigabyte's headphone jack might have an impedance of around 20-Ohms (wild guess), which is not 4-ohms or less, but way better then 100-Ohms.
So you could just remove the Xonar DX and use the Gigabytes on-board audio.
Or Get an headphone amplifier, like the FiiO E11K ($60), which has an output impedance of less then 1-Ohms :)
So plug the E11K into the Xonar DX and the headphones into the E11K.
Or replace the Xonar DX with the Sound Blaster Z sound card, which has a headphone amplifier output impedance of 22-Ohms.