I would be building my new pc soon.
I would be using
Corsair Obsidian D
ASUS P8Z77-V Premium motherboard
ASUS GTX 680 DC2T [2x]
ASUS Xonar Phoebus Soundcard
The GPUs would fit in the two blue PCIe x16 slots and the Xonar Phoebus in the middle PCIe x1 slot.
Would there be any kind of distortion or disruption in the audio quality as the Xonar Phoebus would be right in the middle of the two cards?
[Note:All x16 slots are covered,only one x1 remaining in between the two GPUs which would be taken up by Xonar Phoebus]
I would be very surprised if there was any sort of issue stemming from this. Even if you're running a SLI cable over the sound card, the cable should be shielded adequately to prevent much in the way of signal bleed, and even if there were, I doubt it'd be enough to bother the sound card in any way.
Now granted I don't exactly have an EE degree, so it's always possible someone who does may come along and tell me I'm completely full of it, but I really don't see you having anything to worry about here.