I remember when Perpetual Technologies emerged, very early implementation of up and over sampling, DSP. Some real shenanigans going on with that company! I did have a totally Frankenstein Perp Tech setup at one time, everything completely modded out with help from Dan Wright of Modwright. That was great digital setup, problem was I wanted to stream, no way with that setup.
Merlin, I had totally modded out VSM-MM, wonderful years with those, still have. Bobby commits suicide.
Joule Electra, had totally modded out LA100MK III, wonderful preamp. Judd passed away.
BPT power conditioners, still have BPT 3.5 Sig, very high quality transformers used here. Don't know why they went away.
Audio Logic. I had Audio Logic 24mxl, tubed dac. Jerry Ozment passed away.
Nirvana Electronic Works, N.E.W. I had DCA66, battery powered class A amp. Some people thought this Nelson Pass design, wasn't. Sold in past year to individual who was in group dedicated to restoring these pre's and amps.
Dahlquist. Do they still exist? Still have my DQ10's from 1980's, first nice speaker owned, heard great setups using these at audio shows back in the day.
EPI Epicure. Owned some 100's way back in the day.
Acoustic Research, AR3A's owned way back in day.
Lafayette Radio Electronics. We had local store in neighborhood, way before I was old enough to understand any of it.