Image source: Cirrus Logic's mission and vision statement.

After the closing bell today, analog chip designer Cirrus Logic (CRUS -1.56%) reported fourth-quarter and full-year results for fiscal year 2015. Cirrus surpassed analyst expectations by a wide margin, and also reported more diversity among its largest customers.

Wall Street's consensus estimates called for adjusted fourth-quarter earnings of $0.47 per share on roughly $232 million in total sales. These targets were in line with management's official revenue guidance from the January report.

Cirrus delivered earnings of $0.66 per share on revenues of $255 million, easily exceeding analyst targets on both counts. Cirrus' sales grew 70% year over year, including a $54.5 million contribution from recently acquired Wolfson Electronics. Excluding that buyout-powered revenue bump, Cirrus saw a 34% improvement to its organic sales.

As always, Apple (AAPL -0.82%) was Cirrus' largest customer, but the sales mix is shifting quickly. Last quarter, Apple represented 78% of the company's total revenues. This time, Cupertino's share of Cirrus sales dropped to 65%. Another mystery client covered 15% of the total order volume.

Image source: Cirrus Logic.

This shift reflects "our ongoing efforts toward revenue diversification," said Cirrus CEO Jason Rhode in a prepared statement.

Beyond that, Rhode wasn't willing to dive much deeper into the customer relationships issue. "Our relationship with our largest customer remains outstanding with design activity continuing on various products," he said. "While we understand there is intense interest in this customer, in accordance with our policy, we do not discuss specifics about our business relationship."

While the company didn't share the identity of the new 15% customer, it's well known that Wolfson supplies audio chips to many of Samsung's (NASDAQOTH: SSNLF) mobile products. Samsung appears to be a likely candidate, but we'll know more when Cirrus publishes its full 10Q SEC filing for this quarter. This may take a month or so.

Looking ahead, Cirrus expects first-quarter sales of approximately $270 million. Analysts currently expect $222 million, so the guidance points significantly higher.

In the coming year, Cirrus wants to explore the mass market for mid-range smartphone audio chips. "While the prices for these components may be lower, the potential volumes are large, and we believe our ability to customize our general market products will enable the company to service this market while maintaining margins that are consistent with our goals," the company stated.

Even further down the line, the same audio technologies could trickle down into the burgeoning markets for automotive and home systems, as well. Cirrus recognizes that this extended strategy may take some time to unfold, but the long-term growth opportunity looks tremendous.

Headed into this report, Cirrus shares had surged 59% higher during the last six months. Share prices fell about 1% lower on the news, conserving most of the stock's heady momentum.