OPA227: 3nV

AD8604: 33nV

LF353: 16nV

Also made a better binaural stand.  Despite the cardiod pattern, testing showed spacing them 2ft apart like omni's yielded better stereo separation.

The result was of course a mixed bag.  Both recordings were normalized.  To make it easier, they were made indoors.  Both sounded like noise.  Fortunately, being experienced  flat broke renters, lions know the noise in the 2nd recording is water outside the apartment.  Despite much higher gain, the 1st recording couldn't resolve the sound of water outside & it's very obvious.

It's an extreme difference, from just removing an input op-amp stage.  It makes you wonder how far a preamp could go with better op-amps, single transistor designs, better power supplies, metal film resistors, if time & money were unlimited.  It also shows negative results from Chinese microphones may be from people using crummier amplifiers.

It was a very educational experience, showing as long as the signal is above the ADC noise & the recording medium's noise, the op-amp noise is a significant factor & higher gain is not as important as signal to noise ratio.  In the days of tape & soundblaster 16's, the recording medium was a bigger source of noise than the input stages, so the VU meters needed to be as high as possible.  Those days are over.  Nowadays, you're actually better off with the VU meters down in the weeds.