Topband: Probably-dumb question re current mode chokes on RX antennas

[Pete Smith]

I think I understand that common mode chokes are important on small 
loops and other low-output receiving antennas, in order to prevent 
signals being received on the shield of the feedline and passed 
through the matching transformer primary at the antenna end, to join 
the desired differential-mode signals on the coax which then go to 
the receiver.

But what about the case of a different termination at the antenna 
end, such as a preamp or an active antenna amplifier unit?  Does the 
same still apply, or does the termination in the output of that 
amplifier attenuate the common mode currents sufficiently to make the 
common mode choke unnecessary?

73, Pete N4ZR
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