>- that it IS a concern, that being dangerously close to the negative offset is a risk of using OLDER circuit designs in her old books (before this).
Yes, but the question was "is a negative voltage dangerous". The answer is: No, possibly less efficient but Dr. Clark does not claim that it is dangerous. She only states that an all positive signal is better.
To this date, our data does not support this claim. Not saying that it is not correct, it just does not support the claim.