I would examine the whole chain to see if it is being caused by a specific component.
Yes; I did that and found that removing the concrete pavers under my speaker stands instantly eliminated the sibilance. A year later, after getting the caps replaced in my cross-overs (system was sounding dull) the highs came back, with sibilance. I’ve just recently noticed I hear sibilance when my wife speaks, so I can only conclude it’s now a hearing issue. Having said that, some gear makes it worse, as I discovered when I auditioned a well-regarded DAC in my system.
Thanks for your responses.

