The Ampex 16 Bit Digital Delay Line vs. wire comparison was made in a professional recording studio control
room on time aligned UREI 813 speakers with McIntosh MC-2100 amplifiers.
The audio source was local country artist P. J. Coombes who had been recorded on a 24-track Ampex MM-1000.
That tape had been mixed to a 2-track tape at 15 IPS on a Scully 280.
The mixdown and playback was through an API console.
Thus the master tape played for these ABX trials was of quality not available to the record buyer of the era.
The listeners included professional recording engineers with years of experience on major label projects,
professional maintenance engineers, and recording engineering students.
For those not familiar with studio equipment, these are some of the most revered pieces of equipment of that day.
API consoles are still prized today for their high quality. The studio microphone locker included
Neumann U-67,Neumann, U-87, and Neumann KM-86 along with various microphones that might be selected
for specific applications such as inside the drums.