Not true! I said the reverse: You should try the 440 with the 840 pads. 840 pads are rear vented and 440 low end changes drastically when used with 840 pads.
440 pads on an 840 would reduce low end but the main change would be the highs as the 840 cloth has some acoustical resistance, unlike the 440 pad.
I hope you didn't try the 840 with the 440 pads. Think of the children, Tyll.
Sorry to drudge up this old post. I lurk here from time to time but didn't see this the first time around.