To improve the sound quality of a TV screen on an external audio system; BF amp and speakers; This little box works perfectly. It is connected via optical cable to the Freebox Revolution. The stereo audio amplifier (Devoid optical input !!!) is connected to this case by shielded cable (chinch sockets). After preset audio level on the amp, it controls and adjusts the sound level to convenience ON REMOTE TO Freebox. A real happiness .... changing my TOSHIBA TV (42AV625D) and the appalling problem of distortion and random audio ....