shampoosuicide
500+ Head-Fier
The H40 sound awful on the Zen Dac because the dac is too warm for them.
Ha, well I can certainly see why you'd feel that way! Though I'm running the H40 modded from the Atom.
Would recommend getting a spare set of grilles and swapping out the stock ones (reversible) and/or trying a pair of SpinFits
As for the ZEN DAC, I would give the GTO filter a try, if you haven't already!