Left channel muffled

[stevenjw]

While playing from my iPhone, the left channel is muffled. The right channel is fine. I have confirmed this with ear phones, to Bluetooth speakers, via Bluetooth in my car. I recently received a refurbished iPhone on warranty and so can confirm it is not device related as the issue occurred on my previous iPhone and the current one. I can only assume it is app related. Any help is appreciated!

[wizard64mx]

Same situation with my Motorola G Play with Android 6.0.1

Example: A Day in a Life by The Beatles and The Rover by Led Zeppelin.