All I am saying is that no matter how well I ground the Empeg to the car, there is still some current from the disk and the digital circuitry flowing in the audio ground that makes noise in my head unit and that I can correlate to the disk activity, display changes and/or button pushes on the Empeg.

I do not know what the circuitry actually looks like but it is certainly not behaving like it is optically isolated. In fact, so far it is not any quieter than the Neo-35 that it replaced.

Further, I am concerned that if I tear up the Porsche harness to the Becker head unit (which is totally quiet by itself, playing CDs or the radio through an ADS P640) and go to a star ground configuration then I will still have a noise path through the audio cable shields.

I am not throwing stones at either piece of equipment, just trying to get rid of the noise with minimum modification to the car harnesses.

Lynn