All OpAmp mic design (no FET at first stage)

[Cqwet Dbdfte]

0.001% should be -100dB THD+N, and could be audible depending on its harmonic content. Even orders may be inaudible
I would think most mikes and speakers will not meet that -100dB , and certainly not my ears.
Percent of full scale can also be misleading if not the full scale is used.
I have not seen much of weighing the harmonics against their annoyance factor.
The -100dB number may disguise other more annoying factors, odd order, monotonic noise, intermods, who knows.
Tube amps humble %THD numbers vs. some solid state types would make people cover their ears.
Some people prefer single ended no feedback power amps, with objectively much worse THD.

 

[Matt Syson]

You also have to consider the performance figures for whichever op amp you chose when faced with the circuit you are using it in. Using such a high value feedback resistor (or should it be considered as a biassing resistor only? ) may indicate the original design and op amp uses a topology internal where parts of the usual attributes are bypassed like using the offset input terminals of a LM301 or a NE5534 to input signal from a pair of J FETS (for example) essentially using only the output drive capability an internal voltage gain. This makes basic function of a circuit much more OP amp specific.