If you think that they do not use power when they are turned off, you're wrong. An electrical appliance that is switched on continues to use power. Don't be afraid of misconfiguring your DTTV channels and unplug the cables before going to bed. Some call this spending the ""phantom load"" and it is estimated that it accounts for 2 to 5 MW per device and hour.
The Catalan Energy Institute estimates that the standby power accounts for 4% of the total energy spending. For a moderately equipped 90-m2 flat, this means an extra 51 euros per year.