I'd like to add Polk Audio to this list. Back in what seems another lifetime, I sold a laser product, an electronic speckle pattern interferometer, which could measure surface deflections in microns. A big market for this product was in the design and engineering of speaker drivers, and to this day, I have very fond memories of an entire day spent in 1986 with Matthew Polk and his team at their Baltimore HQ. They didn't buy one ($100,000, even then), but could not have been more gracious nor engaging. I went right out and bought a pair of their Monitor 5's after the experience.

Those, and my first pair of real speakers, Boston Acoustics' A70's, will never be forgotten . . .