mic and mic preamp question

[Rja4000]

The difference in sound is definitely real, but I have no idea what makes the newer gear sound better. I always thought that the converters ands clocking were making the big difference but I could be wrong. It could be any number of other things in the chain.

Measuring such device is quite easy.
Just measure it in loopback: REW, 1kHz, -1dBFS, Output to input.
That will already give you an idea.