Bluetooth Headset Profile and the Nexus 7?
Its not only your device's issue, but also in most of the devices. Android 4.2 has this issue. And Google officially confirmed it . 

Look above link
"We have fixed the a2dp streaming stutter problem on N7. The next release should have the fix.Sorry about the problem." 

Android 4.2.2  fixed Bluetooth audio problems on Nexus phones and tablets. You just try it out by using new 4.2.2 in your N7.