Happy to inform that I solved the problem by removing the three pin cable between ZZ9000AX and ZZ9000.
Instead I made a cable that redirect and mixes the output from ZZ9000AX to the sound output from the Amiga 4000 by connecting ZZ9000AX sound output to sound input on the A4000 motherboard. Removing the three pin cable between the sound card and ZZ9000 removed all static, bus noises and distortion.
That means, AHI works fine, MP3 fine and Paula output is crystal clear.