New Cartridge choice

I know its an old question and one thats impossible to answer, as cartridge choice is so personal, but a bit of guidance would be appreciated. I use an Origin Live illustrious/ Resolution table, currently with a Koetsu Rosewood Signature. I am about to take delivery of a K&K audio phonostage, so I will let that bed in first.
Its hard to usefully audition cartridges and almost impossible to do A/B comparisons. I will almost certainly be buying 2nd user which makes it harder still. I know 2nd hand is risky with cartridges, but I have always done that and had no problems to date.
I listen to classical, opera, Solo Singers, Blues. I find the Koetsu is a great sound, but lacks detail and can sound muddled in complex passages.
My thoughts to date: Koetsu Rosewood Signature Platinum
Shelter 90X
ZYX Airey 2 or 3
I am sure you may have better ideas. One problem is that none of these cartridges appear commonly on E-Bay or Audiogon.
Your thoughts would be appreciated