I haven't the remotest clue which apparatus produced which recording, but I can offer my reactions to each one. I downloaded them, sat in my usual listening chair, and played them through my Pioneer hi-fi with my usual treble and bass settings. There are many variables aside from equipment anyway - furnishings, carpet or the lack of it, drapes and so on, in the listening room as well as the recording room.
No 1: Overall the clearest recording, although the setting is not the intimate one I am used to.
No 2: Sounds further away, more centred stereo, like a commercial CD, as if it is playing outside the wall of my lounge, but seems to lack the clarity of No 1.
No 3: Unsatisfactory, with background static, odd frequencies and interference throughout.
No 4: Wider angle stereo, more intimate, sounds closer, but less resonant than No 1.
No 5: Sounds like No 4 but recorded with slightly too high a recording volume or too much gain.
No 6: This seemed to lack overall richness of sound, as if it had been flattened or normalised.
So my personal order of preference is probably 4,1,2,5,6,3 but I haven't the faintest idea which is which except that 3 is probably the crudest. But as Dave implies, beyond the obvious things get very subjective.