The lightbulb thingies are tubes. You put them in the holes on the amp that seem like they fit. Don't turn the amp on without headphones plugged in. Turn down the volume before switching cans. Turn off the amp before switching tubes. Power + no tubes = magic smoke release.
I all but abandonned fantasy (with the exception of harry potter, which has more to do with my having kids than actually enjoying the writing) about 10 years ago. I still read some SF and horror, tho not much hard sf. Tim Powers, Bruce Sterling, William Gibson, John Shirley, etc.