I have a friend who has hearing impairment due to Military Service. He asked that I build him one of my mods with more highs and stiffer. Upon receiving the amp he decided that it was not to his liking so I requested he ship it back to me so I may rework it giving it more sag and darker tone. I totally reworked the NFB to include the Presence. Then filtering and preamp tweaks. Of course all work at no additional cost, only three preamp tubes (Chinese) & shipping. Part 1. Part 2.