There's a review online by a fella who calls himself Levi I believe, for Enjoy the Music? who writes about the Magic II, and the Silver ref II, perhaps that will get you closer to the truth.
I think there's more to it than just the cabling though... all I heard from many others was the Silver Refs were better in the II version, than before but could sound bright in the wrong system.
It could have something to do with it like Raul said too.. the amount of silver vs. copper, but I'm not sure. I feel brightness might be too much of a good thing, or perhaps not enough in other areas below the top end being promoted and thus the highs are noticed more and become edgy or don't blend well enough into the mix.
I've had all silver over copper cables and some outright silver and they weren't bright. I do prefer a mix of the two, but I'll seldom ask for it and just try the cable as there are so many other variables than just the mixture... connectors, impedance matching... resistance, etc.
My Nirvana SX is a very smooth wire, yet has superb detail and venue retreval. My Magic II follows it as the pre to amp IC.
As I use a preamp, I have other sources with different cables on them, and the Magic does well with all of them and I don't feel I'm losing anything. For the $$$ preowned, I think they do a great job in my rig, with my ears.
I'm sure there are equals and or betters out there... I just haven't found them yet.. and I'm not in the mood to hunt them up right now... so that says something I suppose.
Of course, all these cables are mighty popular so if you got one and didn't like it you could pretty easily sell it again.