I cable tie a DC power cable extension lead to a jack-jack lead and run the two between the pedalboard and the amp, and keep the adaptor behind the amp. Also, never wrap the lead from the adaptor round the adaptor, wrap it into a loop and secure it with a velcro cable tie. But BRX's method, or using a power supply that has a mains input, would be the best way if you have the room and/or the budget.