Phase Linear was an audio equipment manufacturer founded by Bob Carver and Steve Johnston in 1970.
While primarily known as a power amplifier company it also produced several innovative preamplifiers, tuners and the Andromeda loudspeaker.
With 350 watts per channel it soon became the standard amplifier used by recording studios, sound reinforcement companies, professional musicians and audiophiles.
All of those designs were made to have extra power to run loudly the relatively inefficient sealed-box speakers like the Acoustic Research AR3/AR3a.
It shared the same distinctive brushed aluminum, dual VU meters front panel style as the 700.
By that time the company was in decline due to the increasing cost of research and development, and the departure of Carver.