The port doesn’t support bonding with a sub.

The sub can be bonded with devices that have built in amplification, soundbars, amp, speakers, but the port is a playback device that relies on external amplification.

The external amplification means the port wouldn’t be able to do something as simple as balance the sub volume level with the external amplifier and increase/decrease it if the external amplifier volume is changed.

Thank you for the respons