70 volt tutorial:

Wire line loss calculator

 

https://www.crownaudio.com/en/tools/calculators#line_loss

 

Design software tools:

 https://jblpro.com/en-US/softwares/csc-ceiling-speaker-configurator-software-v2-1

https://jblpro.com/en-US/softwares/distributed-system-design-dsd-v3-6-2-v3-6-2-windows