What flintstone said. Also, mike preamps vary greatly in how strong a signal they can take from a microphone before their input circuits overload. Furthermore, any one mike preamp will generally get very different noise figures at different gain settings. Spec sheets generally list only the best single figure that the preamp is capable of getting, which is often at a higher gain setting than most of us would probably use.
Finally, just knowing the raw level of noise in a preamp doesn't tell you how likely that noise is to be audible, since audibility depends not only on the level but also on the frequency spectrum (distribution) of the noise and its properties in the time domain (is it mainly steady noise, or is it full of impulses? The latter can be heard at much lower average levels).
All in all, most specification sheets for mike preamps just don't tell you very much of what you'd most likely want to know. The spec sheets for mixers and recorders that contain mike preamps are worse yet, since the mike preamps are only a fraction of what the manufacturer is trying to sell you.
I'm interested in this recorder, but if it's going to be anything more than a bit bucket, I'll need to know more about its mike preamps. The sensitivity figure given in the spec sheet for its mike inputs is rather high--it seems as if this unit was designed to be suitable for use with dynamic microphones or low-output, consumer-type electret condensers rather than the professional condenser microphones that I and a lot of other people here use. But if the preamps also have high input headroom (if they can handle, say, half a Volt or thereabouts without distorting), then they could be very useful. I guess we'll see.
--best regards
