[Collins] Low impeadance headsets

[Jim Isbell]

I have four David Clark pilots headsets with, among them, 3 different 
microphones.  But I think all of them are low impedance dynamic mikes.  

Is there a  simple but hi-fi circuit that I can insert between the mike 
and a Collins 32S-1?

I want to convert at least ONE of the four sets to be used on the S-Line 
and then I will sell off the other three.  I don't want to sell any of 
 them, though, before I determine that none of them has a High impedance 
mike.  The three different mikes that I have are the  M-1/DC,   the M-4, 
and the   M-101/A/C.  Does anyone know anything about these mikes?  The 
earphones on all four of them work great with the 75S-1