Is it permissible to turn off the lights in the Masaajid in order to attain Khusoo'?
No. This is an innovation. The lights are not to be turned off in the Masaajid during the Taraweeh Prayer... That's because the people are in need of the lights. Also this is an innovation and it's not permissible. It's possible that this is from the actions of the Soofiyyah.