An HDMI coupler is an adapter with two female ends, and it allows you to extend the signal path of a single HDMI cable. But does using a coupler affect the overall video quality of your HDMI connection? Generally speaking, if you just need a few extra feet, adding a coupler to your wire run shouldn't be an issue. It's when you start messing around with two different brands of HDMI wire, or two different HDMI standards, that you may run into compatibility issues. We should also mention that there may be a quality loss with HDMI when you're dealing with longer cables.