EXCLUSIVE: Pacific Ocean Post, the postproduction sound facility in Santa Monica, is closing its doors for good at the end of business today, throwing some 15-20 employees out of work. The company did post sound for blockbusters including The Avengers, Iron Man 3, The Hunger Games: Catching Fire and Despicable Me 2 along with Best Picture Oscar winner Argo.

Pacific Ocean PostPOP Sound’s closure is the latest chapter in the collapse of a once-vast empire of sound mixing and editorial facilities owned by Empire Investment Holdings. Empire-owned Soundelux, Hollywood’s largest independent post house, recently filed for bankruptcy, and its facilities in Hollywood, Burbank and Santa Monica have been closed, resulting in the loss of more than 100 jobs.

Related: Soundelux Files For Chapter 11 Bankruptcy; Pink Slips For 30

“Everything is being closed,” Soundelux bankruptcy attorney Leslie Cohen told Deadline. “It’s moving into equipment liquidation mode under Chapter 11.” And a POP sound mixer said: “I’ve never seen so many companies going down all at once. I absolutely loved working here, and to see it all going down is incredibly sad.”

The wave of sound facility closures “is a big blow to the industry,” a former Soundelux mixer told Deadline. “Soundelux was a major player, and it closed because the cost of sound mixing is going down. Producers can’t keep making things cheaper and cheaper and expect that there’s not going to be any consequences.”

A big part of the problem for independent postproduction houses is that the major studios are doing more of their post sound work in-house, making it harder for the indie houses to survive.