I don't know of any DTS modification for the DVL-9, which I believe was sold in the US as the DVL-90. If the relevant circuitry is similar, which it may well be, you could investigate the DVL-909 DTS modification.
Thats the link I was thinking of, but as i dont need DTS from it I never tried the mod, or wanted to risk it.
Not sure what price I'd sell it for but make me an offer.
I'm buying a lot of new gear at the minute so the moneys handy.