Why is the audio input from the microphone connected to the inverting input on the TPA6111A2?
Any sound picked up by a microphone can be assumed to come from some point distant to the microphone (maybe mm to several metres or more). Take a sound at 1 kHz at 10 metres distant to the microphone. 1 kHz has a wavelength in air of around 0.34 metres and this means that between the source of the sound and the microphone diaphragm, the signal has undergone 2*10/0.34 (= 59) phase inversions.

If you moved the source 0.17 metres closer it will have undergone 58 phase inversions.

I'll leave it to the reader to decide if it's at all important to worry about the phase change effects of a mono source on the listener or any amplification stage after a microphone.