Try the following to resolve your issue:
Poor sound quality from an AUX device
- Reduce the volume level on the connected AUX device. Some devices might output too strong of a signal with their volume level set high or to the maximum. This can cause poor and distorted audio from connected speakers
- Go into the sound settings of the connected device and set any equalization and audio processing settings to "off" or "flat"
- Make sure the 3.5 mm plug is fully and securely inserted into both the device and the speaker
- The issue could be related to the audio cable. Try a new cable
- Try playing another source on the device. For example, try another music app to see if the issue is with a particular app
- The issue could be with the connected AUX device. Try another audio device
- Reboot the connected device. This is typically done by turning it off completely and then restarting it
- Reset the Bose speaker by turning it on and holding the power button for 10 seconds until it turns off. Note: A factory reset clears the speaker's language setting and its paired mobile device memory, returning the speaker to original factory settings