Got a mains cable, don't judge me before you hear what I have to say
So I got a mains cable from my brother who thought it didn't positively affect his system. I plugged it into my Cayin and there was no getting behind the fact that it made a difference. It was like someone added more power to my amp, I got more bass (which was welcome), more detail and the speakers were less "visible" in the soundstage. I previously needed to go to 12 o clock for loud listening but this positioon is around 11 now. I don't believe it either.
The next job was to add it to the Hegel, which already had an impressive stock mains cable. It gave the impression of lowering the amps volume but it was okay since it has an insane amount of power and you could never turn that volume know all the way. There was more silence too.
So using two different amplifiers I got two different results. The result could be what someone is after, the choseal reference mains cable costs about 60 and I think its definitely a keeper if you get the sort of effect I did with my Cayin. I would avoid it with very high end kit such as the Hegel which usually have good mains cables fitted to them. FWIW my brother used the mains cable in his gryphone, dynaudio and stream magic setup and found similar results to what I found with the Hegel.