Numark Mixtrack Pro 2 Audio Issue

Hi folks,
I’m new to Mixxx and I’m hoping you can help me.
I have a laptop running Windows 10, a Numark mix track pro 2, and a external pa speaker.

I have installed Asio4all.

The software recognises my controller. My music folders are visible, the sliders and fader on the controller work and the music is heard via the laptop. Now here’s my problem. I have RCA leads connecting the controller to the powered speaker, but nothing comes out.

I have tried various settings, searched the forums and googled my problem to no avail.

Thank you in advance for any help you can give.

Thanks
Rob