Originally Posted by soundsculpture
It has an c-media processor, two wolfson DAC's, high frequency response and upgradable 600ohm opamp on it.
Well, the C-Media "processor" is not really a processor, as the C-Media Windows drivers do most of the processing in software. The X-Fi card has an EMU 20K2, which is a real DSP chip, and is better suited for hardware accelerated audio for gaming. The Wolfson DAC does not make much difference, and it is one of the lower end Wolfson DACs anyway, with slightly worse specs than the CS4382 on the X-Fi Titanium. Frequency response is unlikely to matter much, since it is usually flat enough in the audible range for most line outputs; advertising a very wide frequency range is more marketing than a real advantage. The "upgradeable op amp" is again mostly a gimmick, and the 600 Ω rating is actually the minimum it is recommended to drive - that is because it is, like the majority of op amps, not quite ideal for driving headphones directly, but it works fine as a line output buffer. If the X-Fi card uses an NJM4556 on its headphone output (I am not 100% sure about that), then that is actually one of the better chips for driving headphones.
To summarize, for games that can take advantage of the features of the Creative card, I would use that. Other than that, for use as a line output (with an external amplifier) playing simple 2 channel audio like music, I do not think there is much difference. Due to the lack of sufficient information, I do not know which one is better for driving headphones, but probably neither is quite perfect. However, upgrading the AD700 to something better that can be driven reasonably by these cards would likely still make the most improvement to the sound quality.
Edited by stv014 - 7/24/13 at 3:20am