Output impedance

Hi,
Looking at the schematic:

www.electrosmash.com/images/tech/pedalsh...ld-uno-schematic.png
The output impedance at the A0 output is:
Zout= R6 + Zout of TL972

If you check the TL972 datasheet (www.ti.com/lit/ds/symlink/tl972.pdf) on page 8 Figure 5, the output impedance at 5V is less than 0.1 ohm, so the total Zout is:

Zout = R6(4.7K) + 01ohm = 4.7K

Meaning that the output impedance at pin A0 is determined by R6 (4.6K).