Roku quietly acquired Danish audio startup Dynastrom for $3.5 million in September according to a regulatory filing spotted yesterday by Variety. The filling doesn't explicitly refer to Dynastrom by name but refers to a privately held technology company based in Denmark. Variety scanned LinkedIn and found several Dynastrom employees, including its CTO and CEO, had joined Roku back in September. The filing states that the acquisition was to "enhance the company’s player product offering" and is the best evidence yet that Roku will be jumping into intelligent multi-room home audio in the not too distant future.

Dynastrom is an audio company that makes software that can be integrated into loudspeaker hardware in order to stream music throughout the house over standard Wi-Fi. Variety had earlier reported that Roku was working on far-field voice control — a feature found on voice-controlled smart speakers like the Amazon Echo — and was busy hiring staff into a “center of audio excellence”.

Roku currently makes some of the best streaming devices for video content. In a previous filling to the SEC, said it wanted to be the "streaming platform that connects the entire TV ecosystem." This acquisition seems to be a step towards that goal. Roku's IPO in September valued the company at $2 billion.