Hi, New memnber and fairly new keyboard player. I am enjoying my new WK7500, but find that when I use the headphones the volume is quite muted. Is this normal or do I have a problem.? Im using the headphone that came supplied with an 1/8 to 1/4 adaptor. Also I have not been able to line out or plug into an amp or pa. How do these sound in a band setting and which way seems best.? Thanks