Poor quality hdmi cable, signal attenuation will be more than 10 meters, over 15 meters there will be no signals.
In particular, the wall at right angles encountered when wiring audio-visual room, also will be affected.
So when it comes to how to choose the hdmi cable, so during these many years, you can go market or go to Some fever forum, or search your own friends, if you find a hdmi cable, hdmi cable which has been successfully wiring more than 15 meters, then no doubt, is the quality of clearance of wire.
HDMI not only communication but also with a number of weak current, so when you plug in or out the HDMI, two devices are turned off or power is best, otherwise, HDMI connector is very easy to burn out.
For example, when you want to plug the hdmi cable, HDMI if this is even a TV and ATV, then TV and ATV should be off.
Sometimes HDMI not plugged steady, in the case of the ends is also very easy to burn powered HDMI interface device.
So my ATV, please equipment and high-power amplifier is connected to a separate switch for each plug wiring board when not in use every day, I will serve them off to prevent children touch by wrong.