Hello, I have a tlm 102 and vtb1 studio projects preamp with a switch of impedance (50 ohms and 200 ohms). I want to know what impedance of the preamp should I use for this mic. In the operation manual of the tlm 102 says "rated impedance 50 ohms". But I hear that is better to use higher impedance on the preamp. I select 50 ohms or 200 ohms on the preamp? Thanks!