I tested Neumann USM69 LDC Stereo microphone in XY cardioids config against Superlux S502 ORTF stereo SDC.

Now this is certainly not a fair comparison, but then, why not?

The test is not conducted 'scientific way' it's rather practice oriented real life situation application test. The stereo microphones were brought as close as possible together and approx. 75 cm away und a bit up from the player; the M160 pointing to the 12th fret approx. 40cm from the top.
Here's the link:
https://www.dropbox…

These are 5 different takes mixed down (corresponding numbers):
- only with S502

- only with USM69
- with USM69, with a mid channel recorded closer with Beyerdynamic M160

which I'm testing for my personal use in acoustically more difficult situations (like playing Classical Guitar or oud with cellom which is quite a bit louder, especially in lively acoustics).

The file names are basically self-explanatory.

I'm curious what you say...

The recording are, apart from mixing in Pro Tools 12 native totally unprocessed 96/24 interleaved wav files.

(recorded directly into Tascam HS-P82)