I owned an Interface ( stevenson) 16x8, years ago . from 74 to about '85. that I used in the 8-track room, ( with an ampex 440-b) very nice sounding board, almost impossible to overload- film sound guys used to use the small ones on set because they were so rugged . But, very primitive, as far as features,( monitoring was silly, I had to wire in channel inserts, and rotary master faders ( separate for each side....), from a modern perspective.
Louis Stevenson took each order, and then they made 'em. and wrote a manual that took into account the specific tape machine that you were going to hook up.
pm me if you want more details...