Again from the Nanomesher site they detail which GPIO's are used for the NanoSound. As I only needed the GPIO's for the display and control buttons the NanoSound plugin doesn't clash with the GPIO's needed for the Speaker Bonnet which are GPIO18 (BCLK), GPIO19 (LRCLK) & GPIO21 (DIN) as I will be using a different DAC configuration in Volumio.
Looking at the details for the Nanomesher Nanosound DAC, the GPIO's that it uses for the control buttons and uOLED display are the GPIO's that are carried to the extra connections on the Speaker Bonnet.
So a quick solder of some header pins (25 way to save you counting) onto the Bonnet for the GPIO's, also Ground and Power which is needed for the buttons and uOLED display.
Oh, and as I got my RPi Zero W without the header pins already fitted so that needed a dual 20 pin header soldering in as well.
Having soldered the header pins and changed the uOLED display to use the I2C interface it's time to work out the wiring.