I haven't heard any of the "Premium" ZYX cartridges, so can't offer any useful input on the visible or non-visible changes or their effect on performance.
Chakster is correct that the (original) 4D is physically different from and audibly superior to the (original) Airy 3. My initial reviews of both have been confirmed by other reviewers and by many listeners via public posts and private emails. (Note to Chakster: I also concur with your take on copper vs. silver coils. I've posted many times that with ZYX, copper is the most dynamic and lifelike, silver less so, gold much less so.)
Don_c55, you didn't say whether you've ever owned or heard a UNIverse (any version), so the basis for your feeling that they're a "rip off" is unclear. I've owned and extensively used the original UNIverse (three of them) and UNIverse II and I'd happily buy either of them again. I also know and converse with many UNIverse owners from around the planet, most all of whom would do the same. I don't know even one who felt "ripped off". Most feel quite the opposite, that the cartridge provides extraordinary performance for what they paid.
Chakster is correct that the (original) 4D is physically different from and audibly superior to the (original) Airy 3. My initial reviews of both have been confirmed by other reviewers and by many listeners via public posts and private emails. (Note to Chakster: I also concur with your take on copper vs. silver coils. I've posted many times that with ZYX, copper is the most dynamic and lifelike, silver less so, gold much less so.)
Don_c55, you didn't say whether you've ever owned or heard a UNIverse (any version), so the basis for your feeling that they're a "rip off" is unclear. I've owned and extensively used the original UNIverse (three of them) and UNIverse II and I'd happily buy either of them again. I also know and converse with many UNIverse owners from around the planet, most all of whom would do the same. I don't know even one who felt "ripped off". Most feel quite the opposite, that the cartridge provides extraordinary performance for what they paid.