Hello Adrian,
congratulation to your first QMX activation!
It was the same here during my first time on a summit with my QMX. But there is a work around: lower the volume. So far as I know, the volume control is part of the digital signal flow. In case of to high level wrong or to large digital values feeding the audio DAC causing distortions.
This is my way to lower the voltage from LiFePo4 4S.
Wish you success with your QMX.
73, Ludwig