Just remember: even if those Eurorack modules can handle the amplification level, you'll still need to extract your desired signal from what'll be a lot of noise. The two solutions for this are either very aggressive bandpass filtering after the preamp to localize the range in which the signals can be found (usually subaudio ranges) or the use of a lock-in amplifier which can "track" the signal as it fluctuates. I'd also suggest making use of several window comparators which can extract voltage level information and convert this into gates, which can then be used as needed.
And yeah, that Grass device I linked to is pretty chunky...but you have to admit that, as unwieldy as it is, that damn thing looks COOL in addition to being one (of several) of the right devices for the task. Not as technologically badass as MY lock-in analyzer (made by EG&G...the folks who also run Area 51!) that's on top of a rack right behind me as I type this, but those Grass things definitely have that "evil guvment lab" look DOWN. Test gear suuuUUUUUcks to haul around...but onstage, it definitely projects a "whoa..." factor!