'Initialize the amplifier.'

def __init__(self, nad_device, name, min_volume, max_volume, volume_step):

    self._name = name
    self.nad_device = nad_device
    self._min_vol = ((min_volume + 90) * 2)
    self._max_vol = ((max_volume + 90) * 2)
    self._volume_step = volume_step
    self._state = None
    self._mute = None
    self._nad_volume = None
    self._volume = None
    self._source = None
    self._source_list = self.nad_device.available_sources()
