Stereomour is designed with using 2A3 or 45 tubes in mind. Paramount has been designed for the use of 300B or 2A3 tubes. In other words, you won't have to figure out anything on your own to use a Stereomour with a 45, the parts are included. A 45 in a Paramount would be best done with different iron, adjustment of the voltages and currents, etc. that we have not worked out.