I just had a view on my adapter which didn´t work for the DMB: 9V 500mA (center negative of course).
The result was only hum and no delay. Bypass and LEDs worked.
I had the same problems with a “wrong?” adaptor (which works for all my other effects). The original EH 9.6V 200mA adaptor fixed the problem.
I would like to know what multiple power supplies are compatible.