Since you have an (ancient but good - indeed!!) turntable and arm, one factor on the side of the 990 is its phono preamp. I don't know if the Emotiva or Arcam units have one. The 990's is moving magnet only, so if you have an MC pickup it's irrelevant. Whether the 990 is as good as your Naim/Nait equipment I can't tell you, but mine is better than the Adcom GTP500 it replaced.
Happy choosing.