Founded in 1974 by Janet Furman in San Francisco, Furman grew out of the Bay Area pro audio scene of the early 1970s. Janet Furman had worked as an audio technician and recording engineer at Alembic Studios — the Grateful Dead's preferred recording operation — and served as one of the recording engineers on the Dead's historic Europe '72 tour. She launched Furman Sound Service as a pro audio manufacturing company, initially building audio and video signal processors for sound reinforcement, recording studios, broadcast, and post-production.

Furman became best known for its AC power conditioners, voltage regulators, and power distribution units designed to protect professional audio, video, and broadcast equipment from surges, noise, and voltage irregularities. The company's proprietary technologies include Series Multi-Stage Protection Plus (SMP+), Linear Filtering Technology (LiFT), Extreme Voltage Shutdown (EVS), and BlueBOLT remote power management. Popular models span a wide range: the M-8x2 rack-mount conditioner for basic protection, the PL-Plus C and PL-Pro C with pull-out lights and voltmeters favored by touring musicians and studios, the P-1800 AR voltage regulator for critical applications, and the P-2400 IT flagship with fully isolated balanced power for mastering and broadcast environments.

Panamax acquired Furman Sound in 2006, and the brand later became part of Nortek Control before being acquired by Italy-based Nice S.p.A. in 2021. Now operating under Nice North America and headquartered in Carlsbad, California, Furman continues to produce power management solutions across its Merit, Classic, Prestige, Elite, and Reference product lines for both professional and home theater applications.

Furman has 69 products cataloged on Equipboard, including Power Conditioners, Effects Processors, and Pedalboards. Their gear is featured by 226 artists, with the strongest followings in Rock, Electronic, and Metal. Notable users include Stephen Carpenter, Dave Mustaine, and Brad Delson.