Q: Bluetooth headphones sound underwater attached to iPhone, sound amazing connected to Macbook Pro

Picked up the Mpow Cheetah Bluetooth 4.0 headphones to use with my iPhone 6.  When I first paired them with the phone, they sounded great, then all of a sudden they sound like they're underwater, everything is muffled.

On the other hand, when I pair them with my Macbook Pro, the sound is crystal clear.

I'm listening to offline playlists in Spotify downloaded at the highest quality.

My assumption is that the phone's Bluetooth is stuck in some sort of low bandwidth mode.

Appreciate any ideas!