Years ago, I bought a nice stereo amplifier: a Marantz PM7200. For around €200 on a dutch second hand site, checked by an electrician and in great state.
What I love about this amplifier, apart from the sound, is its simplicity: it amplifies stereo audio. That's it. No bells and whistles like HDMI inputs, wifi or bluetooth control, not even a tuner. I like this, because those always get outdated. It was introduced around 2004, 20 years ago as I'm writing this, which means that the included extras could be largely obsolete anyway. Hell, even something as an FM-tuner would be near obsolete these days!

What it does do:

• 5 line stereo inputs (RCA)
• 1 phone stereo input (RCA + GND) for a turntable
• Pre-processor in-/output (bridged together normally)
• 2 stereo speaker outputs

If you ask me, technology that is still relevant in 20 years to come.

A year or so ago, I got sucked in the world of home automation. I personally don't really see the need of automations that detect when I get home and turn on the lights, I mostly use it for making small things in life easier like being able to turn on all my lights at once.

One requirement I always had though: it should always be controllable without internet. So a lamp should always have a physical switch to control it, additional to wireless control.

This is also what I want for my amplifier. When I want to turn on my (internet)radio, I can do that using the remote that came with the Marantz. I've built a clock some years back, also featuring a IR receiver and a Raspberry Pi with LIRC to process those commands. The amplifier though, I have to turn on myself, with a physical, clunky switch at the start of the mains circuit of the amplifier. It does feature a standby mode, but I'm not a great fan of it in this amp. I've had it fail on me a couple of times.

Furthermore, the remote has been showing it's age, especially the volume buttons. I've fixed it with some pencil once which improved it for a while, but it has worn out again, so a goal was born:

• Be able to switch the amplifier on/off remotely
  • Not by using the standby, but by actually switching mains to the amplifier
  • But as mentioned: also be able to turn it on/off with a physical button!
• Add volume control
  • So I can also control it while working at home without turning the physical knob
• Modify the amplifier itself as little as possible
  • Maybe I want to sell it at one point and I want to be able to easily put it back in its original state
  • Apart from that: I definitely do not want to mess with the audio circuit

A project is born.