Having problem adding NAD mediaplayer

Configuration
1

Hi community.
I’m having issues adding an NAD mediaplayer using the nad platform.

configuration.yaml:
media_player:
 - platform: nad
   host: 192.168.1.19
   type: Telnet
   name: C390D
   max_volume: -20
   min_volume: -70
   volume_step: 2
   port: 23

error log:
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/helpers/entity_platform.py", line 312, in _async_add_entity
    await entity.async_device_update(warning=False)
  File "/usr/src/homeassistant/homeassistant/helpers/entity.py", line 476, in async_device_update
    await self.hass.async_add_executor_job(self.update)
  File "/usr/local/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/src/homeassistant/homeassistant/components/nad/media_player.py", line 200, in update
    self._volume = self.calc_volume(self._nad_receiver.main_volume("?"))
  File "/usr/local/lib/python3.7/site-packages/nad_receiver/__init__.py", line 83, in main_volume
    return int(self.exec_command('main', 'volume', operator, value))
ValueError: invalid literal for int() with base 10: '-42.0dB''

I hope somebody can help. I’m not much of a programmer. But is the platform trying to dB to an int?
Regards.