the manual say “Power zones should be used to isolate different genres of equipment from each other. For instance, you can group digital equipment together on a single zone and multiple analog sources on another zone. You should not mix digital, video or analog equipment on the same zone.”
Some devices combine two categories, for instance integrated amplifiers including headphone DAC+amplifiers from; Benchmark, Bel Canto, Simaudio, and Grace. How should I treat them if plugging them into a P5? The current draw and range will be pretty modest, so this may be more academic than real.