This just about meets the brief, primarily 'cos I drilled some holes and soldered a handful of wires
https://thepihut.com/products/adafruit-stereo-20w-class-d-audio-amplifier-max9744 was sent to me in mailshot, so got Mrs Normula1 to buy it for my birthday. Rummaged through my boxes of bits for all the other parts and a wall wart power supply for an external hard drive to power it.
Fired it up briefly this evening and it won't win any awards in the cork sniffing stakes but it def works.
Stereo in and out, in theory 20 watts per side but can't see me getting anywhere near that with my 2amp PSU.
One word of warning is that the onboard power connector is centre positive.
Comments
( PS the long tail on the -ve looks like it might touch the case at some point, you might want to clip that )
I gave it a workout over the weekend and yes it works, not convinced I'm too enamoured of the tone. I built it so I had something to use whilst I rebuild my valve power amp (a couple of the valve sockets have gone after 60 odd years of use and can't retension them)
But you could just as easily use a pre-amp pedal. I've nearly convinced myself to buy a Boss IR 200.