It took me two LED transformers for our double bed - the old 20W halogen lamps were to me has always been a thorn in the side - as they are pretty hot. This I have exchanged using two lamps of transformers against 3W LED.
The transformer I have attached with double-sided tape behind the headboards. Should also mean: even the already can not stand me the ticking of a watch on the bedside table - there are no humming or whistling noticed :-)