Hello Jokeyman123, Sorry I didn't reply sooner. I haven't played the piano much, which by the way is a PX350, and I bought it off eBay. It's in excellent shape, well taken care of. I definitely hear a difference in sound. I'm talking specifically about the D above middle C, nine notes above. The sound of that D is not as rich and wholesome as the surrounding notes. I checked all the piano sounds and the electric piano sounds and that D does not sound the same to me. I'll get in touch with Mike and see what he thinks. I thought it was a sampling issue, but maybe it isn't. Maybe there is some dirt in the sensor. If I do decide to take it apart, is it relatively easy to clean the sensor? I'm pretty handy so I wouldn't have a problem tackling this.