Analog out on STM32L432KC

Hello all,
I’m playing with DAC on a Nucleo-L432KC and mesure a voltage range 0,03V … 3,29V directly on the pin. Is it possible that the output-buffer is enabled with DAC output?
If so, is there a chance to disable it? I’m using external buffering to scale up to a 0…10V signal.
mbed studio 1.3.0
mbed-os 6.6.0
AnalogOut aout(PA_4);
Any hint in the right direction would be appreciated.
Thank you!
BR, Walter

Edit: after digging around a bit I found the file:
where I modified line 85:
and that did the trick!
But I think it is no good practise to change files directly in mbed.
So my question is: how to do this in my source?
Thanks again!

BR, Walter