The problem has been reported before but i forgot about it:
It remains a mystery to me why the postinstall script runs on some platforms but does not on others, even with the same npm and Node.js versions 
Only thing I can come up with at this moment is something that might be a workaround:
- Connect to your DietPi using ssh
ssh root@<ip address> - Install the Denon extension manually with the
--ignore-scriptsoption
npm install --ignore-scripts -g https://github.com/docbobo/roon-extension-denon.git - Now get to the Extension Manager on your Roon Remote, select the Extension Manager from the System category and perform the Restart action
- Open the Extension Manager again and go the the Denon extension, it should be reported as Stopped. You can now perform the Start action.
With these steps I get it running on DietPi but I don’t know if it works correctly as I don’t own a Denon or Marantz receiver.
@Jense, @Andy_Spinks, please let me know if this works.