Frederick, Darren,
The 110k resistor is mainly to make sure that the op amp outputs aren’t floating when nothing’s connected. They will create a high pass filter, that’s why the value is relatively high.
It does not mess with the output impedance, as it is in parallel with the output (and two resistors in parallel will always have a resistance below the lowest value resistor).
You will see more changes from the original CNC circuit, as this is my take on this textbook phono stage. The input impedance values are (imho) more useful, giving you 17k to 150k in fifteen steps. The variable gain is done in the second gain stage, after the RIAA equalization, to avoid clipping the higher frequencies.
This circuit also gives you selectable gain of 36-46 dB in four steps, and the RIAA equalizer circuit has been improved. It has lower resistance which means lower noise, it’s not as sensitive to changes in component values (even outside of normal component tolerances), and all components are standard E24 values so you won’t have to search for components that are hard to find.
Finally, even though this board is larger than the ones in my kits, it’s smaller than the CNC boards. It’s even got ground fill, and it will slide into a B0905 enclosure without having to do any drilling.
The design files for my power supply are available here: https://www.muffsy.com/blogs/post/Make-Your-Own-Muffsy-Power-Supply/
It’s fairly easy to etch yourself, as there’s very little copper that needs removing. Alternatively, order it from the fab house of your choice.