Run the check
Record a short silent-room clip at the same input gain.
Compare another port or a different wireless location.
Repeat with a second input device while keeping the room unchanged.
Read the result
Noise following one cable or port is different from room-wide sound.
Limits and next step
Listening alone cannot identify an electrical component failure.
Repeat the check after changing one setting or connection. Keep a record of what changed before deciding whether the device needs service.