I always end up replacing my acoustically recorded kick drums during mixdown anyway. I like the kick sounds on the DR 670. Would love to just eliminate the middle man and go straight to tape with sampled kicks. I see alesis makes a trigger i/o midi pad. Would that work in tangent with the DR 670 to use as a trigger for double kick?
I can't see why not.
Roland also do a trigger-to-MIDI converter, the TMC-6, the Alesis is cheaper.
If budget can stretch to it, proper triggers fitted to the heads of the drums involved may yeld better results, the Roland RT-10K is a trigger designed for kick drums.
Once the converter has taken the trigger signal and made it a MIDI signal, any MIDI source could be used, be it your DR-670, a dedicated sampler, or VST package on a computer.
I have a Yamaha RM50 drum module, this also has 6 trigger inputs. It could work as a trigger-to-MIDI device too, and use a microphone, or tape output as a source (replacing drum sounds off a recorded track).
I never used it this way, so I can't comment on how easy it is, expect much tweaking of parameters!
A E-drum / V-drum module will do the same as above, so an old module without it's kit might be an idea to think about, as it could act as a source of sounds too.