The supplied Eventide TimeFactor PSU adaptor is unregulated, I measure 13.48 volts off load and 11.84 on load, so using a 12 volt regulated supply should not be a problem. Running a digital program, with no pedal or switches attached, a drop of 1.64 volts was measured on the Eventide PSU. At 1.2 amps the PSU is rated at 9 volts so approximately this gives an internal resistance of 7.5 ohms. Therefore this gives an approximate current draw of 218ma. To account for any peak current and full load requirements I would at least double this. I use a TREX ?Juicy Lucy? Fuel Tank (5 X 12 volt isolated) with two of the 300ma outputs coupled in parallel (The polarity needs to be reversed also) to give 600ma and this works fine. I gig in a professional function band.
This is for information only and if you choose to use a different PSU than the one supplied by Eventide it is at your own risk. I hope this helps and clears up some of the mystery, all best and good luck.