Bi-radial lenses like the CH-3 will attenuate the top end of the compression driver's response, so compensation wouldn't hurt. However, I don't think you will need as much with that compression driver. Wayne's compensation circuit takes into account the natural rolloff of the PSD2002's as well as flare modification.

If I remember correctly, the Selenium compression drivers all go down to 1,000 Hz or so (agian, if I remember right) I would urge you to try taking it that low. If not, a 2nd order LP at 1.5 kHz with impedance compensation will handle the peaking adequately, coming from a guy who has owned a total of eight K15lfa's.

Adam