CD players/DAC spitting SSS reproduction

I know exactly what you mean and it does sound horrible! I think that what you are hearing is the recording, and no a transport or dac should not change or filter the signal. Bad in bad out.

Not sure if it is all in the recording as if you listen to an LP of the same song, sibilance is much reduced if not absent. Seems to me digital is adding to this effect.

I had that experience too. Then several changes made it go way. I changed transport and DAC to NorthStar 192 upsampling and 50% of it went way, then I changed tweeters. It is gone or nearly gone.
Yet I think both changes gave me more detail and neutrality in that everything sounds more natural, dynamic when dynamic, and relaxed and smooth when called for, with much more clarity of timbre. I can more clearly hear the female singers in-breath for example, but no more spitting.
Also there is now much more difference between bad recordings and good ones, yet more recordings sound better.
Rest of the quipment is ss with Aragon 28K pre and 8008BB amp, and Polk SRS-SDA 2.3 speakers. So the harshness is IMO not inherent in the media.

I'm sorry, I mispoke, I did not mean it could not be a combination of the gear and media. I have just noticed that certain songs on certain albums, whether vinyl or cd, display that nasty sibilance while other tracks on the same selection do not. Certainly bad digital reproduction can sound very harsh especially in the upper extremes, and a better rig will do a better job. The same can be said for a bad vinyl setup as it will strain as well. Any flaws in the media will be exagerated by the weakness in the system. But on the other hand in my experience, some recordings are bad and cannot be "fixed" by any gear. Often it seems the more open revealing and transparent the system becomes the more "unlistenable" some material becomes. I think we are all correct.