public function addSpeaker(SpeakerInterface $speaker): ControllerInterface
    {
        if ($speaker->getUuid() === $this->getUuid()) {
            return $this;
        }

        $speaker->soap("AVTransport", "SetAVTransportURI", [
            "CurrentURI"            =>  "x-rincon:" . $this->getUuid(),
            "CurrentURIMetaData"    =>  "",
        ]);

        $speaker->setGroup($speaker->getGroup());

        return $this;
    }