What do I need to do to add MP3s

[byTheo]

First of all. Just love your project. I've tried to add an MP3. Downloaded one form notification sounds. But when It's being played on the ESP2866 it's over distorted. Did you convert them? If so how.

[CosmicMac]

Glad you love the thing. :)
I do nothing special concerning the MP3.
Maybe you should adjust the gain?
Please, try http://www.universal-soundbank.com/sounds/21763.mp3
=> MQTT message {mp3:'http://www.universal-soundbank.com/sounds/21763.mp3',oncegain:0.1}
It works flawlessly on mine.

[byTheo]

I might have a broken MAX98357A. Because it distorts heavily 7 of out of 10 times after power up. Or a bad Wemos. I'm powering it up with an iPhone USB adapter. I have a spare one. Will try that one first.