harvie wrote:It's more about size and being compact and easy to use than about money. it would be vital for speed of prototyping.
I understood that most expensive part are electrolytic DC decoupling caps.
However it's true you often need to use some kind of amplifier and these already have DC decoupling capacitors on them, so it might be possible to omit these on raspberry and only supply the PWM low-pass filter made using ceramic caps which is probably way cheaper than electrolytic DC decoupler caps. So it would be easy to use with amp modules that already have own DC decoupling. And if one would need to use it with headphones or something similar, then it would be relatively easy to add two electrolytic capacitors by own means...
alternatively leaving unpopulated pads for these components so people can supply them on their own directly to zero board if needed... that would be extremely cheap for manufacturer and quite handy for users/developers. Especially with PWM lo-pass already on board. You just solder two SMD or thru hole electrolytics and you are ready to go. Similar has already been done with unpopulated pads for external wifi antenna connector.
I don't understand your problem.
You need an amplifier. It has an input jack of some sort. So you put two resistors and a capacitor for each channel between the jack and the amplifier circuit board.
Why should I pay extra for what I don't want, to save you the five minutes it'll take to add the extra components to your amplifier?
You might get away with not adding those components, if the amplifier has a low enough hf-cut-off.