D&M Holdings, Inc. (commonly "D&M" or, later, "D+M Group"; Japanese entity 株式会社ディーアンドエムホールディングス) is a consumer-audio holding company founded in 2002 to merge Denon and Marantz, originally with headquarters in Japan (Tokyo; the Japanese entity is now based in Kawasaki, Kanagawa). It is not publicly traded. Ownership has changed repeatedly: RHJ International, then Bain Capital (via Tokyo vehicle K.K. BCJ-2), then Sound United (Charlesbank-backed, Feb. 2017), then Masimo Corp. (2022), and since 23 Sept. 2025 it sits within HARMAN International, a wholly owned subsidiary of Samsung Electronics, which bought Sound United for roughly $328M. U.S. operations were run from Mahwah, New Jersey (D&M Holdings U.S., Inc.). A 2017 San Diego Union-Tribune report put D&M at about 850 employees globally; revenue is not separately disclosed.
Operations. D&M is an operating consumer-electronics company — historically the world's largest supplier of A/V receivers — not an NPE. Its brands include Denon, Marantz, Boston Acoustics, HEOS (wireless multi-room audio), Polk Audio, Definitive Technology and Classé, covering A/V receivers, hi-fi components, headphones, loudspeakers and home-theater systems, plus a D&M Professional division selling Denon/Marantz AV gear to studio, broadcast and commercial customers.
Litigation posture. The database shows a single tracked case, in which D&M is a defendant with zero plaintiff-side suits — the profile of an operating company targeted by a patent holder. It was named in Digital Security Systems Corporation, LLC v. Samsung Electronics Co., Ltd. et al. (No. 2:08-cv-00316, E.D. Tex., Marshall Division, filed 11 Aug. 2008), alongside its subsidiary Denon Electronics (USA), LLC.
Context. The plaintiff, Digital Security Systems, disclosed Acacia Research Corporation as its corporate parent — a patent-assertion entity. It asserted U.S. Patent 6,052,780 on encrypted, self-decrypting digital information products (DRM) against a broad group of Blu-ray player vendors and retailers including Samsung, Best Buy, LG, Panasonic, Philips, Pioneer, Funai and Sharp. The suit was filed in the Eastern District of Texas, a venue then favored by NPE plaintiffs.