G9's phantom could be simplified by TL783 phantom supply as used in Ian's Classic Solo and other mic amps designed by him, it doesn't need additional load for testing.
If you are thinking of making it p2p i can post my psu needing one less heatsink than G9 because HT is made of capacitance multiplier with zener stabilization. Noise is very low, only heater regulator gets warm, oldest supplies of this type made on a good quality perfboard with some snap in caps are doing fine mechanically and electrically after 15-20 years. I would use pcb instead if more of them had added phantom and no nonsense circuits. They are simple to make either way.