For all those thinking of upgrading an old Intel Mac to a new M Series Mac they are great machines.
However the new unified memory architecture and the fact that it is not upgradable post purchase makes your decision on RAM at purchase a major factor in your future enjoyment of the system with Audirvana.
There have been many articles about this in the Apple focussed media recently. A link to some simple basic advise from Macworld is attached. I have used the M series Macs since inception and I would not consider a machine with less than 16GB RAM for Audirvana due to my use of upsampling algorithms and a desire to conduct this and buffering within physical RAM without recourse to using a swap file.