For a compact case i might start with a PAM8302 from adafruit as i had good experiences with it combined with small speakers before.
Yeah if that is your thing but 2.5W at 4Ω, 10% THD prob means 1.5watt approx max and for me sort of pointless as would rather just not bother and have an indicator and may be cast audio somewhere.
Always wondered why max is often rated @ 10% THD as who would want to listen to a device being overdriven as that?
The 50watt above means to me yeah approx 30watt.
I think its because of different use cases. I use the speaker only for tts to give feedback, like telling me the weather, how much time is left on my tea timer, what time it is or even the news.
For this i find the PAM8302 more than sufficient even in a bigger room.
Of course if you want to listen to music or other media the bigger amps will be much better suited but will also give you a much bigger form factor and in this case why not cast/trigger/send the audio to a real speaker?
The biggest reason would be to do aec with the output signal.
How warm do those amps get?
Need a 12v 30/40mm fan on 5v prob if enclosed in a case but actually run fairly cool.
You would have to try as the pi when enclosed also quickly builds up heat when passive.
When it comes to mini I like the idea of atomic but rather than witt.ai stream to rhasppy.
https://www.aliexpress.com/item/32819907815.html?
£2.50 and extremely tiny 30x35mm
But we all have different opinion and preference, but when you can get a echo dot / google mini for $20 it questions all of us to what we are actually making.
I have had a look at the code even though my C is non existent it is actually all running on a singular core.
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You’re talking about this card, aren’t you ?
Do you get any noise with it. I’m looking for a good way to power a small speaker in a small case. All I’ve tried so far are too much noisy.
Its the ratings Pep as 10% THD @ prob into 2 ohm provides the wattage rating so when your driving this you are driving to hard.
You just need to over spec and lower the volumes on your output.
The above is 3 watt into 4 ohm @ 10% THD and with lower inputs set by output volume it might be OK but overspec even more.
The TPA3118 will run off a 5v supply importantly has a mute switch as they are all buzzy in idle.
Often you need to apply a DC blocking cap to the output but depends on load resistance.
4.7uf - 47uf as a guestimate, or higher as the speakers are not bass capable.
But what you might think is a huge output @5v with a good input level bears no relation to rating.
Also have a look at alsa hooks as you might be able to use so that gpio auto mutes via a 2n2222a transistor.
The 5v input reduces availability and a 12v supply and running the Pi on a 3amp buck might be a better configuration.
Its also the same with ratings on speakers as the reality is usually very different.
If you take the above its 15% THD @ 3watt and 3 watt is maximum and not continuous and the reality is that is not a 3 watt speaker and you need to over spec.
Its only when you get larger and by better manufacturers they actually quote usable ratings.
https://uk.rs-online.com/web/p/speaker-drivers/1345563/
That is a 10watt speaker into 4 ohm.
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I find it good for when you are constricted in size and only want to drive a single speaker.
The sound quality especially when used in combination with a usb soundcard is quite good. I have used it in combination with a few different small visaton speakers and was quite suprised by the results.
It also has a shutdown pin to turn the speaker off when your not using it via a gpio pin.
You will have route all the audio to the channel you are connecting the amp to as its only mono but that is easily done in the asound.conf.
But due to power and size it will of course not drive giant speakers.
For example I use it in combination with a 5w 8 ohm speaker and find the quality good for listening to the news or poscasts.
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This looks very nice - sturdy and functional. Did you print it yourself or via an online print service? Do you an idea what having it printed would cost?
Thanks for the hint! Collected it today and got superb results. (I’ll not hang it up for the time being…)
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Hey Johannes,
any news on this project? I’m ready to put my pi4 + Respeaker v2 using your node-red project in a nice casing! 
Best