I just ordered a HiFiBerry Amp2 for my kitchen and am looking for a loudspeaker to run in in my kitchen. I don’t want to run a set/pair, it’s okay if it’s a single loudspeaker in stereo, like a sigle Sonos loudspeaker.
I bought a couple of speaker drivers from RS Components (Visaton Round Cabinet Speaker, 30W nom, 50W max, 4Ω) and put them in a shoe box. They cost about £8 each and sound great.
A bit late, but.
For my kitchen system I use a single Kef Egg speaker with a Pi 0W and an Adafruit Mono 2.5W Class D Audio Amplifier (PAM8302).
It sounds excellent and is quite loud enough.
You can sum the stereo signal to mono with a passive resistor arrangement.
Is that what you are looking for?