The Threshold SA/1 monaural Power amps. Together with Mark Levinson Ltd, the Threshold company built high power solid state amplifiers even before Krell Industries - the name we often associate with highpower Class A amps - even existed. The principal designer of Threshold, Nelson Pass, grounded his firm in 1974 together with Rene Besné who took care of the PR, sales and beautiful multi-layered frontplates and stylish logo. In 1975 their first product was the Threshold 800A a so called sliding bias Class A amp. To his dismay this topology was shamefully copied by lots of other manufacturers that thought you could produce amplifiers with mediocre powersupplies a handfull of active components and a badge reading something like 'New Class A' or 'Class AA' but they never sounded as good as the original.
Yamaha´s high-end FM Tuner. In the Seventies several Japanese audio companies tried to develop state of the art products to challenge the mainly American dominance in this field of electronics. A typical US highend audio engineer had often former experience in companies that built electronic equipment for the department of defense or other fields of science like nuclear physics or the computing industry. We are all familiar with the term 'Mil Spec (Military Specification)' which is a typical American term for a part is rugged enough to be placed in a military device. Those parts were also used in highend equipment in the US maybe even just for their advertisement value ... What I want to point out here is that the US audio industry could draft it's talents from a vast reservoir of highly skilled engineers from other fields of electronics.
The Model 7 monaural Power amps. Appearing as the last company after MLAS, Threshold and Krell, Rowland Research now the Jeff Rowland Design Group - thanks to the Roland keyboard company that threatened to sue the namesaker of this firm if he did not change the name of his company - had a hard time muscling in the establishment of highend amplifier designers. Jeff Rowland started of by making custommade designs for individuals in the seventies. Later on at the beginning of the eighties Jeff designed a three piece pre-amp and his first Class A, FET input and Zero feedback amp the 2080 (20 Watts stereo, 80 Watts in bridged mode). In 1983 Dr. Roger West of West Laboratories (SoundLab Electrostatics) asked Jeff to develop a powerfull and stable amplifier that could drive his newly designed A1 electrostatic speaker.
The SRD-2000, Spectrals Professional Processor. Even for most audiophiles Spectral Audio needs a introduction because it's a unique but low key audiomanufacturer. Situated in the heart of Silicon Valley Spectral Audio was founded in 1977 by psychologist Richard Fryer who already worked at audio-companies when he was in college. The only other high-end pioneers in the amplifier business in that time were Audio-Research, Mark Levinson and Threshold (Nelson Pass). Their debut came in the same year with the dual monaural preamplifier MS-One that had some novelties like a superb noise free single-gainstage MC phono preamp and matching highly-accurate RIAA equalization. In 1980 the MS-One was superseded by the DMC-10 that proved to be the basic layout for decades to come.
The ML-2 monaural Class A poweramplifier was the first amplifier from Mark Levinson Audio Systems (MLAS). This was Levinson's statement on how a reference amp should be built. At the time (1976) it simply had no peer. Prototyped by John Curl, one of the technical consultants Levinson often used for its company, as a JC-3, and finalized by Thomas P. Colangelo the chief technical officer at MLAS. It is considered as the archetype American high-end solid state audio poweramplifier. Graced with a thick 19 inch wide black anodized frontplate, beautiful sculpted handles and white lacquer filled engravings it has a certain style that would never go out of fashion and formed the mold for a lot of derivates from competing companies. Not only could it supply Class A power to almost any load but it also had a fully regulated powersupply and a modular construction.
The Wadia WT-2000 & Wadia 7 cd-transport. Almost all serious manufacturers of audio amplification started off with separate units like pre- and powercombo's from the likes of Audio Research, Marantz, McIntosh, Quad and later high-end companies like Levinson and Threshold. Some of these brands put out integrated amps as well in a later stage, maybe due to a management directive they had to expand their market like the Levinson ML-12/11 separated integrated amp which was a strange kind of compromise. Of course most high-end companies would feel safe enough at a certain time to offer the same quality in a more convenient and financial obtainable package like a integrated amp. With the introduction of the Compact Disc format for half a decade all CD players were one box offerings although at a cognitive level the two functions of the CD player are pretty distinct.