I have both the Sussurro and A90. I compared them using a Teres Illius tonearm mounted on a Teres 265 table. The turntable drive is a Teres Verus. My phono preamp is a Channel D Seta L.
After spending considerable time setting up both cartridges (using a CartAlign for overhang and zenith, an usb microscope for SRA and the Fieckert Adjust+ for azimuth), I did some extensive listening.
First thing I found was that break-in is absolutely critical for both cartridges. During break-in the A90 gets smoother and less strident, while the Sussurro opens up and reveals much more detail. The first 15-20 hours on the Sussurro produced a truly dramatic improvement in resolution of musical detail.
Once the major changes from break-in were in place, I fine-tuned the SRA for best sound and listened to a variety of music types through each cartridge.
Bottom line, it is a very, very close call between these two. They are both truly outstanding. The A90 is very slightly more open, detailed and neutral. The Sussurro has somewhat more natural sounding voices, and I find the overall sound a little more involving than that of the A90. Nonetheless, these are, without a doubt, the two best sounding cartridges I've ever owned.
The title of "which is best" will, as always, be determined by the personal preference of the listener (listening to their favorite music using their associated equipment), but, based on my experience, the choice will not be an easy one.
