Human hearing can easily tell the difference between one real plucked violin and three real plucked violins.

Telling the difference when reproduced through a loudspeaker will depend on the transient coherence of the loudspeaker.

The direct sound seems to be more important than reflections here. Human hearing is very good at distinguishing direct sound from reflections. It has to be in order to accurately locate threats.

However, if the direct sound is blurred then our hearing can't do much to sort it out as this blurring doesn't occur in nature. Instead it tells us that the sound is artificial.