I thought my input was going bad on my JP7 because when you try to mute the guitar for silence, there is a static hiss that almost seems random. Maybe a bad connection. I also switched guitar cables, etc. I was using my friends guitar to finish recording because his did not have the hiss. Well today he restrung his guitar and now his does the same thing. I clipped all the excess string and made sure nothing is touching anything but now even in his guitar we are getting this static hum after muting the guitar. You can hear it through the amp also. So its definitely coming out of the guitar. Any ideas?