Solution - maybe.
I have had this problem on an Ipad 3 streaming music over wifi (spotify) and sending to a logitech bluetooth adapter plugged into my stereo. I get brief dropouts in the music every minute or two. It worked fine until the upgrade to IOS 6, and I can still use the bluetooth adapter for streaming music from a Windows laptop and an Android phone without problem.
It only happens on the Ipad when wifi and bluetooth are used simultaneously, so you can stream music and play it on the Ipad (or via a cable to the headphone socket) or you can play music already downloaded to the Ipad via bluetooth without a problem.
An upgrade to IOS 6.01 didn't fix it, neither did re-setting my router and trying a different channel, re-pairing bluetooth or a reset of the network settings.
Yesterday I noticed the option to reset all settings.
Go to Settings-General-(scroll to bottom of page)Reset-Reset All Settings
I then had to reconnect to my wifi network and pair with the bluetooth device again.
Having already reset the network I didn't really expect it to make any difference, but today for the first time in weeks I have been able to play music without any dropouts.
I have seen some posts where people have found the problem has resolved itself without them doing anything so it's possible that this is just a coincidence, but it is worth a try as it only takes a couple of minutes. Just make sure you know your wifi password.
Hope this works for you. Good luck.