With the AX421, you can effortlessly switch between two sound devices using the HDMI-ARC or HDMI-eARC port of your television. Connect two soundbars, headphone amplifiers, or AV receivers and conveniently switch between them without having to unplug the HDMI cable. The switch automatically detects the last activated device and switches to it. Perfect for using eARC audio formats: To take advantage of all the advanced eARC features like Dolby TrueHD or Dolby Atmos, ensure that both your TV and sound device support HDMI-eARC. The AX421 ensures that you can enjoy the best sound through your preferred device at any time, whether it's the soundbar or the AV receiver. Practical and efficient: The AX421 is powered via the USB port of your TV and automatically turns on the sound system when you turn on the TV. When used without USB power, the sound device must be activated manually. Note: The AX421 only transmits audio signals and does not pass through video signals. If you are using an AV receiver, connect external players directly to the TV. Compatibility: The switch works seamlessly with all common audio formats over HDMI-ARC (LPCM 2.0, DTS, Dolby Digital, Dolby Atmos) and HDMI-eARC (LPCM 2.0 – 7.1, DTS-HD, Dolby TrueHD, Dolby Atmos). This means you can use your devices in a versatile and flexible manner.