I mean even assuming that this was strictly a 2-layer board, you can still route traces underneath parts like ICs, connectors, etc.. I could believe it was a simple board (for a phonograph and all), but I'd be interested in seeing how well it actually matched. Did he get a new board fabbed and it just worked?

He said that it got a few resistor values wrong, but other than that it was correct. I assume it was actually a single-layer board. (Nobody's doing this with a mini-ITX motherboard.)