Diagnosis
This is often digital audio clipping from a mismatched audio format or a faulty HDMI connection.
How to Fix It
First, change the soundbar's Digital Output setting. Press the SETTINGS button on the remote, go to 'Digital Output', and change it from 'Auto' to 'PCM'. Test. If the crackle stops, the issue is with the source's bitstream signal.
If That Didn't Work
The HDMI cable is failing. Even if it worked before, cables can degrade. Replace the HDMI cable between your source (TV or player) and the soundbar with a new, high-speed certified cable.
Heads Up
If using Wi-Fi for music, the crackle could be network interference. Test using a Bluetooth connection instead to isolate the cause.