I think what is happening here is that the Sansamp PS1 has a “50/50” switch which sends 50% of the signal to the FX loop and the other 50% straight thru to the power amp. With KILlDRY enabled on both Eventide (H9/TF) the one EX PDL in the H9 controls the “wetness MIX” of both units, whose maximum ratio levels can be set independently in relation to each other. So when the pedal is backed off only the DRY 50% of the signal is heard. Which of course is quite advantagous for dynamics. The more the PDL is depressed the more both FX are introduced up until fully depressed. There the FX are fully expressed. I do not know why the PDL engages both units but the 50/50 switch is a neat addition to the Sansamp.