The "DP-UB824EGK" device from Panasonic can indeed convert 5.1 or 7.1 channel content into stereo output.

- It offers analogue audio outputs, including 2-channel (stereo) outputs, where the audio signals can be downmixed from 5.1 or 7.1 channels to 2 channels.

You can set the "Analogue Audio Output" to "2ch (Downmix)" in the device settings to convert the audio output to stereo.