Do not use correctly allows two HDMI devices it is supposed power, not only at the same time, which is normal (the HDMI standard being sensitive to signal phase shift problems) but even separately. It is not enough to turn off unused equipment, it must also disconnect. Additionally different lengths of wires between devices can be sources of disturbance. As if that were not enough, a double taken quickly stopped working, poor contact without doubt one of the pins (twenty). Suddenly, I serve myself on the other taken as a mere extension cable ... 30 cm!
