Look at the watts on the name plate. Divide watts by 120 to get amps. It will likely on a headphone amp be less then 1 amp. Multiply by 2 or 3 and that will be a good size fuse. I'd use 3, many would use 2.
Jerry
Need help with a fuse
Hey guys I need some help can somebody help me please I bought a little dot mark II headphone amp it doesn't have a fuse in the back I know it takes it F1al 250 volt fuse but I have no idea what amp fuse ? I have looked all over online and I cannot find what amp fuse to use would really appreciate somebody to help me out.