Thanks for all the great suggestions. 12 hours of continuous run-in helped open up the speakers. Frustrated with the sound of the Yamaha I replaced it with a Naim UnitiQute2 and Naim Naca5 speaker cable. This provided a BIG jump in performance. The bass was still tubby and one-note, I replaced the factory flat metal jumpers with 2 inches of multi-strand 12 gauge speaker wire. This improved the bass and made it much more tuneful. Finally at the advice of the Forum, I spread the speaker out towards the corners and toed them in 45 degrees. Now I think I am hearing what PWK had in mind. My office space is small (11x14), I place a couple of Vicoustic bass traps in the back corner. No doubt the room will need a few more treatments to get things right.
Next step will be to get a proper digital cable to feed the Naim UnitiQute.