The song most identified with mid 1975 – “I’m not in Love ” was a huge hit that put 10cc on the map in the USA. This is from a Japanese documentary about 10cc (with band members today). Using now revealed “secret” recording techniques that created sounds years ahead of it’s time (before synthesizers were common). To me it was fascinating, but you’ll need to know Japanese to understand the narration.
listen to Part 1
Part 2
Part 3