Mr. Kolton got the bright idea of manufacturing his line to Apple’s market-busting specifications. He flew to Cupertino, Calif., and made the pitch. He figured he would be one of many entrepreneurs with Apple in mind, but that was not the case.

The market got more crowded after Beats by Dr. Dre, founded by Andre Young, known as Dr. Dre, and the music producer and executive Jimmy Iovine, introduced its first $300 headphones in 2008.

“Before Beats, $300 for a headphone was considered an outrageous amount of money to spend,” said Jamey Warren, the chief executive of Headphone.com. “You could buy a Sennheiser HD 600 over-the-ear headphone for $300. It was considered the world’s best, and it was a stretch for most folks except audiophiles.”

Increased demand isn’t the only thing fueling the boom. Crowdfunding sites have given potential entrepreneurs new routes to capital, while manufacturing costs have fallen. The 2014 sale of Beats to Apple, for $3 billion, also ushered in a new wave of headphone hopefuls.

Steve Guttenberg, a contributing editor to the digital products review site CNET and a high-fidelity expert, explained how the business has changed.

“Thirty years ago, when someone said, ‘I want to make a headphone,’ he would probably try to make it here in the United States, or he might design it and then get on a plane and say to the people who make headphones in China: ‘Here’s the design. Can you execute it?’” he said. “Now, we’ve eliminated the first two steps. The requirement, quote unquote, is that the person who’s running the show knows what it should sound like and look like and feel like and is able to say, ‘Keep showing me your samples until I find it.’”