iPad Pro HDMI / Audio Jack via USB-C - Volume stuck on full

Hi All,

I use my iPad as the centre of my Karaoke solution using Karafun (cloud Karaoke solution).

I used to run audio out of the jack up the top of the iPad and VGA / HDMI from the Thunderbolt jack at the bottom.

I bought a new iPad Pro and a USB-C adaptor with HDMI Port, Audio Jack and USB-C Power (to keep the iPad charged while being used all night.

The trouble is the audio coming form the adaptor is full volume and I cannot adjust the volume for the iPad itself.

I understand this may be due to the fact that HDMI is grabbing the Audio signal and another adaptor vendor called it out as a limitation of iOS....

If someone knows of a USB-C adaptor that would provide me with HDMI and Auxiliary Audio Jack out I'd appreciate it. If it's even possible.

Never thought I'd be having to go back to my old iPad v6 to run Karaoke!

Any input welcome.

Thanks

Mark