Hum when power supplied by daisy chain

For convenience and because the supplied BB adapter is not really high end quality (poles are a bit loose and feel wobbly) I tried to hook up my BB to the daisy chain which supplies power to two other (Boss) stomp boxes. Unfortunately this results in a very annoying hum on my bass amp/cab.
The wall socket is grounded but then none of the adapters are.
As soon as I use the BB adapter (in the same socket) the hum disappears.
Anybody with the same experience and preferably a cure?
Thanks in advance,

Probably good to know that the BB’s signal is not connected to my bass amp but goes directly into a PA.

Apparently BB requires close to 500 mA.
The daisy chain adapter supplies 1300mA but the two Boss pedals plus BB exceed 1300mA.
As soon as I disconnect the Boss pedals the hum is gone.
My conclusion is I can replace the 0.5A BB adapter by any other 0.5 9V adapter when needed.

There’s quite a bit here on the forum about the pros and cons of using daisy chained power supplies.