As computer audio devices got better I felt a need for a better amplifier for my PC with more inputs so I could still have my SNES and Genesis connected. I also wanted to be able to see the level of the audio signal. This prototype had electronic input selection via four push-button switches on the front wired through logic into a special IC, the National Semiconductor LM1037N stereo audio switcher. The output of this amplifier used the LM2879 Dual 8-Watt Amplifier IC, also by National Semiconductor.
The photo shows it sitting on top of my PC. The power button was a push-on/push-off type with a single red LED for power indication. The level meters used LM391x ICs and 10-segment bar graph displays I got from RadioShack. Input selection was done through a push-button selection of the desired input. It also had a cooling fan to keep the amplifier cool at sustained high volume conditions (frequently). All of this was mounted inside an aluminum cabinet (also from RadioShack). While I no longer have the schematics, I generally built things in a modular fashion using the reference diagrams from the various datasheets for prototypes. Only changing things as needed to customize for the final version.