boost::shared_ptr<GainControl> _gain_control;
boost::shared_ptr<SoloControl> _solo_control;
boost::shared_ptr<MuteControl> _mute_control;
boost::shared_ptr<GainControl> _gain_control;
boost::shared_ptr<SoloControl> _solo_control;
boost::shared_ptr<MuteControl> _mute_control;