I found this site on the Internet saying something to that effect:
Warning!!.....Never connect and disconnect HDMI cables and equipment while your devices are powered on (hot plugging cables). The hdmi cables carries a low DC voltage while connected. You will damage your equipment and the HDMI Distribution equipment while hot-plugging cables which will not be replaced under the 1 year manufacturers warranty. Only use the Switched Mode Power supply supplied with the HDMI Equipment since replacing the power adapter might damage your equipment if incorrect voltage is supplied to the equipment.