Hum from speakers.
Since the introduction of the PurePower+ There have been 2 customers who suffered from hum that appeared in their speakers.
By definition, hum emanating from the speakers represents an unwanted signal that has entered the audio signal path through one of many possible routes. In the particular cases that the hum appeared after installing a PurePower+ unit we very strongly suspect the path is through a ground loop. We suspect ground faults because of our prior experience with similar symptoms over the years that were resolved by finding and eliminating ground problems.
We do know that there is no inherent electrical characteristic of the PurePower AC output capable of affecting the audio signal through the AC supply. Nonetheless we returned both units to our factory to be absolutely certain they were operating perfectly. They were.
We suspect we have not convinced these now former customers that with perseverance, the cause of the hum could have been found and eliminated through the right diagnostic method and signal tracing tools. Unfortunately we could not resolve the issue and they are now operating without the benefit of our product. I think it is fair to say that both expressed a clear wish that they could enjoy the PurePower benefits hum free. Thus, they are hoping we will be able to modify our product in some way to solve the problem.
For our part, we wish we had the time and resources to make house calls and help them install our product and find and remove the real hum source.
So our answer has to be no we are not working on fixes for hum by changing the PurePower electronics because we are absolutely certain PurePower technology does not, and can not, cause hum.