If you have a 4K display and a 1080p display you may want to hook up one device that displays on both. An HDMI splitter will do that for you, But other splitters will examine the displays hooked up to it and send the lower quality resolution of the two displays to both displays. This could result in a 1080p signal being sent to the 4K display. The echo split solves this problem by sending each display the highest quality signal they can receive. In the example before, the echo split would send a 4K signal to the 4K display and a 1080p signal to the 1080p display. This is also assuming the source signal is 4K.