Step-up Transformers? Which impedance setting....

[Mikey]

would work well with the largest range of playback heads?


I may add a pair of step-up transformers to my tape head preamp,
as I've got a pair of Cinemag CMQEE-3440A's that I'm not using:

http://cinemag.biz/mic_input/CMQEE-3440A.html

I can wire these transformers to obtain several input impedances,
either 37.5, 150, or 600 ohms.

Which setting would work with the widest range of heads?
What would happen if a high impedance playback head was
mated to transformers wired for 37.5 ohms?

Mike