resistors - Line level to microphone level to record - Electrical

Resistor - Wikipedia

impedance - Circuit to Convert Line Level to Mic Level - Electrical Engineering Stack Exchange

Differences Between Mic Level and Line Level

Powering Microphones

Dynamic Microphone Amplification – Naiant Studio

Audio input - TechWiki

Understanding Audio Level

Microphones: Levels & Gain — AudioTechnology

Understanding Audio Level

Understanding Impedance

Line Out to Mic In 52db L-Pad – Life At Warp 9