Buck Frobisher wrote:

signal generator, and a distortion analyzer, allowing up to four units to be
compared at one time.

Four of what type of units? Amplifiers, turntables, preamps or what?

All the rage for the well-heeled audiophile or service department in the
early '70s!

Ah, the zany 70s! I can just see Hef in his smoking robe checking the
performance of his 4 stereo systems.

-ex