- Verify all levels (Volume, EQ) on the speaker are set accordingly...

- If you are not sure of what channel should be set...Set all levels at 50%

- Check all audio connections between the audio source and speakers...Depending on the setup there could be multiple connection points.  Start from the source and make your way to the final output point which would be your speakers or headphones...

- Verify levels of other pieces of equipment in the audio chain..(media players, controllers, amplifiers, mixers, etc)...

- Assure connection points between sources are properly secure...

- Verify mixers, amplifiers, and other input devices are receiving signals...Usually, a signal is indicated by an LED...