Isn't hat due to the Curtis chiop they use?
I remember having read about this "filter bleeding" several times. Can't remember if this was on all DSIs though.
EDIT: yes, the CEM chip,
DSI-120, designed for DSI exclusively, is used in P08, Mopho and I guess it is present in Tetra as well.
Here, for french readers.
I'm sorry you were disappointed mate.