did you put your Air to sleep with headphones attached, or closed the monitor with phones attached?
Do not sleep your Air (close the monitor with headphones attached) with headphones attached, this is known to affect some Air under Mavericks.
* this occurrence is being looked into.
Much testing on my own and others as well show that, in some instances, this occurs in Mavericks.
If you choose you may contact Apple for an appt and diagnostics.
However as said, refrain from having phones attached when you close the monitor to prevent this until it is resolved
Test this and re-verify
have personally tested disabling power nap, doesnt work in 2 diff. units.
Audio Plist deletion hasnt been tested personally however others indicate it not working.
in which case if in effect a reboot would have to occur regardless.
The use of the APP Boom will also induce this fault if present at time of sleep.