I finally had some time to work on diagnosing the problem of the buzzing. The first thing I did was to disconnect & clean all of the cables & verified that all of the connections were solid. With the help of my son-in-law we followed the suggestions offered here in the thread. We also connected another CD player to the "suspicious" DAC.
Unfortunately we could not get the buzzing to reoccur. At this point I don't know if the cause of the buzzing was associated with the cables/connections or possibly the dreaded intermittent electrical gremlin. So going forward I can only wait for the buzzing to reoccur & then to connect the DAC to another CD player.