Some writers have technical skills, while others spin out profitable junk for acceptance by gullible editors and readers. De-gaussing (there are no ferromagnetic materials in a disc), polishing (introduces millions of microscratches that distort the laser beam), and trimming (can worsen track eccentricity or unbalance), have the potential to degrade, but not improve, CD or DVD disc quality. If this remains an issue, Media Sciences would be glad to participate in a controlled test on a few discs, both before and after the "improvements", at no charge and then publish the results online. Please contact me if you wish to participate.
As stated, power demands by optical drive servos can generate adverse feedback to a DAC through the power supply.