When you hear a great performer, do you ever wonder, "What violin are they playing? Is that a Strad?" A common assumption is that all violin soloists are playing on the violins of Antonius Stradivarius. Many are, but not all.
Then there are those lucky few that own and play on more than one great instrument. Two Stradivaris or a Stradivarius and a Guarnerius. Hmm, what should I play tonight?