I had an extra Shure transformer from another project, and thought it would be cool to have a stompbox-sized Level Loc to run a dynamic (or tube) mic through for a "smash mic" drum sound or other lofi uses. It runs off a standard Boss 9V supply. Mic in, unbalanced line out. Cheap and cheerful.
This one. What you can't see is that the XLR goes directly to the input transformer, which goes to the top and bottom of a 50K input pot. The wiper and bottom (ground) of the pot go to the input of the circuit.