Koestu original Onyx Sig pre-platinum cart vs. later/current platinum Sig comparisons

I’ve recently acquired a previously owned Koetsu Onyx, but would like to find out more about its vintage. It has black blocks with unthreaded mounting holes and a black upper side with ‘made in Japan’ and ‘18333’. No P before the serial number. Is it correct to assume this is a pre Platinum version, or are there platinum versions without that P? The box only has the three letters ‘PLO’ handwritten in pencil. With some fantasy this might indicate PLatinum Onyx, but obviously anyone could have scribbled this on the box. Does anyone here know what version this might be?

I have more than 30 cartridges but this is my first Koetsu, believe it or not. I was not impressed by hearing a Rosewood in my own system a few years ago. So I lost interest in the brand, for a while anyway. While this Onyx sounds much better than my memory of the Rosewood, I’m still not overwhelmed. Any tips on getting the most out of it?

PS: I followed the general consensus and started with an FR64S with SUT (Ortofon T-3000). When I moved it to a Micro MAX-237 with solid state mc phono amp it opened up and sounded more powerful and dynamic. Anyone tried it with current gain phono amp?

'Stratus seekers for status seekers' is the way I once heard someone describe Koetsu cartridges. As in 'somewhat cloudy, misty and warm sounding' having an irresistable attraction to people who believe that buying a Koetsu is the entry ticket to some exclusive club. It's the same kind of pride of ownership you can observe with other luxury brand goods. There's nothing wrong with that of course, but it's a lifestyle thing and has very little to do with the sound quality.

I acquired a Koetsu Onyx some time ago (no 'P' in the serial number, so presumably a pre platinum version) to find out for myself what all the fuss is about. I still haven't a clue, although I've tried all I could to make it sing. It's been installed in 5 different tonearms, in voltage and current gain amplification devices, in 2 different SUT's (one copper wired, the other silver) and with a wide variety of headshells, leadwires and tonearm cables (balanced as well as unbalanced). But no matter what I did, to some extend it would always sound congested and with a limited bandwidth. I have to assume this is their sonic imprint which sticks to it like white on rice (or brown as it turns out). Apparently there are a lot of folks who (think they) like it that way. I don't, but at least I satisfied my curiosity. Exit Koetsu.