Want very high impedance preamplifier? We may have many circuits to do. But the FET Preamplifier circuit might be good choice. Because of small, easy, and cheap.
Want a high impedance preamplifier circuit? For a ceramic record player, etc. Make the emitter follower circuit has low noise causes sound concise.
Try medium Impedance Preamplifier circuit using only one transistor. Use a common emitter. Have a lot of circuits use this. try it and learn with fun.
Make the easiest Low impedance input preamplifier circuit using transistor and a few components. With PCB layout and how to reduce hum and low noise output.
For maximum efficiency, reducing various problems well. Let's know the characteristics of CMOS and how to use it.
Your amplifier may sound better than before. Just change the appropriate power supply circuit. Multiple levels of output voltage. For example 15V Dual regulator for pre amplifier. And 38V Dual for main amplifier etc.