[morzh]

The rep, as you can see, has said exactly what we had said before. You need 10K impedance.

As for the turns ratio, it is the simplest of all:

1. connect the primary of your transformer to a Variac and inject, say, 20V in it (measured with the primary connected). This is your Vin.
2. While continuing injecting the voltage in the primary, connect the meter to the secondary and measure the voltage. This is your Vout.
3. Your Vin/Vout ratio is your turns ratio W.

Now,

4. Your Turns ratio squared times your output impedance (say you have 8 Ohm) is your primary impedance. Say you have W=35 (you measure Vout = 0.57V at Vin =20V). Then your input impedance is 8*35*35 = 9800 Ohm which is what you need.