I tested every single chip with my HardSID SE (4 chips at the same time) playing 8580 TestSong with Acid64 Player (where you can switch between the voices an filter to test it)...
This ICs are original 6582A remainders in new condition - just once for test used (carefully!) n' they are no rebranded 8580s anyway...
I'm not an impostor, my offer is true! And the price is fair, cause it was hard for me to find them on earth, war of nerves I can tell you! I don't need all chips, so I sell 75% of the ICs to you - if you like.
Picture shows the last test session n' final config for my hardsid, maybe it's imagination - but I would say that they sounds better than the two 8580s I had installed before.