I'd put the A90 ahead of those other cartridges too. As I posted back on 10/01/11, "...I'd at least consider putting it on a similar plane to the UNIverse."
Any cartridge that comes close to a UNIverse will outplay lower range ZYX's (including the Omega, which is a lower range cartridge regardless of what it costs). As to outplaying those Koetsus, this isn't so difficult.
The A90's among the best 5 or 6 cartridges I've heard. Glad you're enjoying!
