Using LED Matrix in free Running Mode

I recently started a project where I do a FFT on a line input signal. I want to use the “free running mode” of the adc to get a high sampling rate of my signal.
I am using this led matrix to visualise the bins: Medium 16x32 RGB LED matrix panel - 6mm Pitch : ID 420 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits
The Matrix uses some of the Analog Pins to adress the rows in the matrix.

My question is, is it possible to use this display when in “free running mode” or vice versa will the display interfere with this mode?

So far I had no luck getting solid results like this, only when I use analog read.

That display is going to take most of the processing power of your Arduino so I can’t see you getting good results with your components.