I use the phatom power to supply the GCP through the Triaxis phantom output. I linked it in my TREX fuel tank ( 500 ma) . I need the TREX for some pedals too. So i dont know how many power left for the other pedals.
Can i use 12v for the GCP?
How many ma. need the GCP¿ is the same ma when you use phantom?

Thank you so much

I wouldn't go below 400mA. Your 12VDC output should be ok for this. Current draw should be the same powering directly vs phantom power aside from the slight load a long MIDI cable might add.

I hope that helps!