Making an API 312 clone play nice with -10db gear

I've got an API 312-esque clone that I've pieced together from some old Tamura transformers and a Whistle Rock 2520 opamp. I'd like to experiment with a piece of gear that accepts a -10db line input (Teenage Engineering OP-1, for those of you who must know.)

I imagine that swapping the output transformer (currently 1:1, 600 ohms) for something with a lower ratio is the answer. Please, someone let me know if I'm way off base. Also, if a new output transformer would do the trick, how might I go about calculating the appropriate ratio?

Thanks!
Swan

What about an output-attenuator? Like a T-Pad ore something?
You could leave the transformer and pad-down the signal after the TX for the desired level to the next stage.

regards,
Wolfgang

ArrGh!... Wolfgang posted while I was Typing... So, basically the same here:
  Look at how Jeff at Classic Audio Products of Illinois (and others) do this : add a 600 ohms T pad atternuator after the output transformer as a way to push the pre hard without hitting next gear in the chain too hard. maybe a solution for you as well.
Laurent.

1k log pot