I’m now kind of curious, exactly what kind of gear and recordings bring this problem out?Its a distortion problem. If you have a problem with the setup of your phono cartridge (or its suspension is shot) you can get sibilance.
Another way this can be caused is by a bad driver in a loudspeaker. A woofer that has a shot suspension can introduce sibilance that can sound for all the world as if its caused by a tweeter. A rubbing voice coil can do this too.
I've had a variety of speakers and amps yet not encountered the issues described by @dekay above. I started with the original American pressing of the Trinity Sessions and then eventually found the the Canadian press, which is a little more immediate. Neither version had any problems, which is why the recording was popular with audiophiles. Is there some peakiness in the recording? Sure, but not the point of sibilance.