[Elecraft] K2 calibration curiosity

[2Cents]

Good day group,

I've used the XG2 to calibrate the S-meter of my K2 and got calibration
results of S-LO of 191 and S-HI of 007. My 50mv input results in an S-9
signal (6 segments on the bar graph), turning off the XG2 results in 1 bar
flickering. So far so good according to the book.  The curiosity is this:
with 50mv applied to the input, if I turn on the ATT the S-meter drops to
only 2 bars illuminated.  Conversely, if I turn on the Preamp all the bars
become lit.  That seems extreme to me, but I seek the common wisdom.

I've fairly recently done a pretty through recalibration under the tutelage
of Don Wilhelm (thanks, Don!) so the radio is playing well, but the s-meter
response makes me wonder if I should be looking for something that needs
correcting.

Thanks and 73,

Chuck Teague NN7U