We've had some issues with audio fidelity in pairing with older operating system Macbooks. Users have been experiencing muffled sound in some units.
For some, this has been resolved by updating to most recent version of OSX.
At higher volumes, we found some units drawing so much power onto the amp that it was dropping the voltage to the Bluetooth Module. This caused some interference in signal. In some cases, this could be solved with a battery charge, but in a hand full, we had to replace the battery or internals.
If you have this issue.... hit up firstname.lastname@example.org and get it sorted under warranty.