NLS HiFi

According to David Kay when I asked if they were ever produced:
They never went into production. They made less than a 100. ... The idea for it was a collaboration with his top electronics technician, Sam Messin. They were both audiophiles. We had only MacIntosh stereo systems in our house when I was a teenager, the Non-Linear days.
That was one of his first attempt at a consumer product and as I explained earlier marketing was not his forte.

Electronics August 9, 1965 article