Brad and Joe, Thank you both for your responses. My son does use headphones most of the time but if he wants to play out loud so others can hear, headphones would not be practical. In regards to the "hiss." I may not be describing it accurately. Basically, it sounds similar to stereo or car speakers when they are "blown," often from playing to loudly. Can this speaker on the piano be replaced? If so, where would I get one and how can it be replaced? In regards to the amp connection. When plugged into the amp, no sound comes through at all but the amp works when connected to other string instruments. Thanks again!
