1. Ensure that all cable connections are secure.
Please check your speaker, interconnect, and ground cables for damaged or loose connections.
Ensure all bare-wire connections to the equipment or speaker terminals are secure.
If you installed your own terminal ends on your cables, please check that these are properly secure and undamaged.
2. Check your Input Source's Audio
Check to make sure your audio source is active and that all input cables are secure and undamaged.
Please make sure your audio source is line level. - If the input source offers volume or mute control for example, you may need to make adjustments.
Alternatively you can also try a different source which may help in identifying any problems if they come from your source.
3. Ensure that you are not charging a device via the USB port and using it as an audio source at the same time
4. Move the unit away from other electrical equipment that is likely to cause interference