Being a musician, I regularly use these cables from my primary amplifier to my speakers.
They are rated lower voltage <50v, but fairly high amp at a max of 40 RMS I believe.
I find it interesting he is using PA speaker cable connector in his application. They come in 2 and 4 pole versions. An 8 pole is available but looks nothing like the one in the photo. I suspect the one in the photo is a 2 pole version. I believe the Nexan 3G 2,5 is a 3 strand cable, 2.5 mm, which would match the 2 pole Speak On connector. (2 pole plus ground)
He is either a musician or someone working with him possibly is. These connectors would probably not be well known outside those circles.
: I noticed this too. May be he found a very good, highly linear amplifier for the signal shape he needs! May be one that everybody can afford!