Thanks very much for these suggestions.
Strata's are not bi-wireable (only two posts on each). I have run the polarity tests for both the amp and the subwoofer. Also, the pre-amp has polarity options which I tested. Essentially, I've been thru every user-available combination with no change in the anomalies I'm hearing. Note, that I have also changed equipment, wiring, and room characteristics when I moved the speakers into a small office (wooden floor, 12'x12') and connected to the Onkyo receiver and CD player with same results as before.
Only three options left I can think of: 1) the speakers are somehow defective, 2) they require much more break-in time, 3) this is their inherent sonic character.
Thanks again.