Many devices don't respond properly when connected to an unpowered USB hub when the computer resumes from hibernation.
Now,t his may not be an issue on a Mac. It's not my area of expertise.
But it is something to consider.
Third option is the best and most reliable.ok back to wiring
since i have to get an amp now too
is there another power supply i should be looking for instead of the P9100 that will power everything , if such a thing exists?
or do i do what ive seen other people have done
wire the amp with a wiring harness into the existing mazda connector and jsut use the power unit to supply mac/monitor/usb hub?
or i guess third option
wire amp and P9100 into the battery?
Not to say that using factory wiring won't work. But the safest bet is wiring straight to the battery.