Thanks for the lead. Interesting idea\application if not complex.
Beauty of using the input trans with a moreso conventional attenuator on the secondary is that it is much more straightforward in concept and execution and it sounds pretty darn good... and you actually have many choices in what type of attenuator(series, ladder, broskie hybrid) or potentiometer (Alps, PEC, Penny&Giles) you can use. If building an attenuator you have many choices in which resistors to use, what attenuation slopes you want to use, etc.
Mike