Has anybody tried using single solid core cables?

At a recent hi-fi show an exhibitor auditioning $47K speakers repeatedly asserted the following: "Any solid core wire, even $0.03 a foot is better than any multi-strand available. Experiment for yourselves, you will be amazed."

My question before I ditch my multi-stranded Audioquest Indigo cables in favor of 4 individual single solid core 18 gauge cobber cables from Home Depot for my newly acquired SA Mantra 50s, has anyone tried using single solid core wires?