> ... the dynamic range of mics, which is closer to 80 dB ...

jerryfreak, signal-to-noise ratios for microphones are calculated in an unintuitive way: downward from 1 Pascal, which is equivalent to about 94 dB SPL. That's why you see spec-sheet values such as 80 dB even for professional microphones. It's like giving the s/n ratio of a power amp based on only a 1-Watt output, even though the amplifier might be capable of 300 Watts per side.

In practice, measuring from the noise floor to (typically) the 0.5% THD point, good condenser microphones can have a "working" range of 120-130 dB. Subtract the CCIR equivalent noise from the maximum SPL (even though the noise is frequency-weighted and somewhat time-averaged while the max. SPL is not) to get an idea of this.

> -130 dB EIN is the stated input spec at 150 ohms

Equivalent input noise (EIN) for microphone preamps is usually reported in dBu, not dBV; because of the different reference voltage, the dBV number is ~2.2 dB more impressive looking. (Tsk, tsk.)

EIN also depends on the impedance that the input "sees"--in actual use, the output impedance of the microphone plus its cable--but you said that 150 Ohms was specified, and that's completely normal. As I recall, the physical limit for an input referenced to a 150 Ohm driving impedance is something like -127.5 dBu--I don't remember the tenths digit for sure--but -130 dBV could simply be a rounding off to the nearest whole decibel of the EIN of a preamp that comes very close to the theoretical limit.

Many other good preamps for decades have come within a fraction of a dB of that limit, but the usual professional practice has been to use dBu, and to round the result to the nearest tenth of a decibel. So -130 dBV looks better, but isn't really. Anyway, even the quietest microphones are audibly noisier than that.

--best regards

P.S.: Even more important than those small fractions of a dB: Spec-sheet noise figures for preamps are nearly always obtained with the gain cranked all the way up--which is where the best numerical results are obtained, even though few people use such settings very often.

I did a rampage of preamp comparisons eight or ten years ago but I wanted to measure the noise at gains I typically use in concert recording, so I set them all for 30-35 dB gain. *The rankings changed drastically as a result.* In my opinion, preamp EIN (and maximum input voltage) should be specified at a variety of gain levels--say at 20, 40 and 60 dB.