Thanks for the response. It’s a positive tip and I have several OEM 24 VDC wall warts (120 VAC for use in US).

The reason I am inquiring about the 27 VDC is because I have three unused isolated 9 VDC power plugs in my Furman SPB-8 pedalboard. Connected in series with a custom cable they will produce 27 volts and I can eliminate having to deal with the wall wart altogether. I am just concerned if the Zener diode in the Q-Tron can handle a constant over-voltage. Sometimes older things are over engineered, then again sometimes not!