nDAC Burndy plug or not?

As I switch my PS555 between nDAC and CD555 I wonder if I can let the nDAC Burndy cable remain in place when the PS555 is used for the CD555 and still play through the nDAC, or is it necessary to fit the plug in order to play the nDAC?

No, if a power supply isn’t connected to the Burndy cable on the Naim DAC then you’ll need to remove it and fit the link plug.