@purrin I wonder if just a non-sighted, leisurely test would be more palatable. Just ask your wife to flip a coin (Head = Modi2; Tails = ODAC), she logs which one she hooks up. You listen for the day and take notes at your leisure. Repeat for a week. Then compare the log with your notes. Instead of trying to determine which DAC is which, just see if you can note sound characteristics that seem to follow a DAC. Takes way longer, but observational biologist basically do this for years. EDIT: Of course, you are blind to the DAC you are listening to, but you are not trying to directly compared them. You will compare them only through your notes.