I am currently building a radio - sound card interface for my IC-730
so i can use PSK31. AIUI, the mic that came with the rig contains a
preamp, so presumably the radio is expecting an audio level above a
usual mic. Does this mean I can simply use the audio level from the
sound card straight into the Mic input on the radio via a 1:1
transformer for isolation, with no need for a voltage divider to bring
the level down?

Thanks.