Mechanical whine - 2001 Honda S2000

I have a 2001 S2k with 96k miles. It has a noticeable whine (like a bearing noise) that increases with speed. It changes loudness and pitch only with vehicle speed. It does not matter whether I am accelerating or decelerating, rocking from side to side, braking, or even if the engine is turned off and I’m still moving at 35mph. All 4 calipers have been removed and wheels rotated listening for bearing noise. Tranny and differential fluid are topped up, smell ok, and show no evidence of metal particulate. Have tried jacking first one rear wheel and then the other and running up to some speed, but still cannot replicate the problem while jacked. I think I have eliminated wheel bearings, tranny bearings (except perhaps rear bearing), differential bearings (except perhaps carrier bearings), brakes, and other stuff that I can think of. Any diagnostic suggestions would be gratefully received.