SHIELD TV Audio Bluetooth Input routing to HDMI output


I want to use Bluetooth microphone linked to the Shield and so get the audio from this MIC and from the Shield thru the HDMI output.
I’ve done some test and for now, as soon as I “pair” the Bluetooth Microphone dongle, no more audio from the HDMI output.
This is to be used like a karaoke system, using Kodi to play karaoke file and get a microphone all together on the HDMI output.
Is there any solution ?

Thanks in advance.