Streaming audio to external amplifier

I’ve attached the RasPi to the AUX connector of a Kenwood amplifier. Streaming audio results in a low sound volume. Any ideas to raise volume through KODI settings?

One of the problems you might be having is that the headphone output from the Pi is not a line level output which the amp will be expecting. When I do this, I have to turn my amp up to the 12 o’clock position.