As I research and work on this from my Raspberry Pi 400 laptop, I realised that the Pi 400 has no audio output aside from HDMI. That's fine for most use cases, but not all. I would love to have a headphone jack on the Pi 400 for times when I want privacy, to drown out the noise of the world, or to stop from being rude or annoying people. This would be useful for children as well, so parents don't have to listen to the annoying, repetitive sounds that kids seem to love so much. I'm n exception; I spent much of my very young years annoying the hell out of the adults around me. A small onboard speaker would also be useful as well. The headphone jack would be great for listening to music while working as well. I know my headphones won't reach the TV's headphone jack. 

I'm havng trouble finding a solid way to get a headphone jack working on the Pi400 right now, but I worked 14 hours straight yesterday, so I'll give myself an excuse this time. I could probably buy some sort of HAT for audio output, but I want something I can integrate into the board as a standard feature or add on. I'll do more research on this later and maybe order a few audio boards for testing. I want to keep it all simple and open enough that people could tinker with the audio themselves as well. This reminds me of adding an audio card to a vintage PC. Some didn't have any audio output, or maybe just a beeper. I think it would be quite fun to integrate an audio card into one of these carts. 

The best I've found so far is  Pimoroni's Pirate Audio Headphone Amp. It's rather expensive at $25, but would give me a good place to start. 

Another good option, though lacking an amplifier for headphone use is the UDA1334A I2S Stereo DAC breakout board from Adafruit.

Of the two options I've found, I prefer the simple and cheap Adafruit breakout board. I can learn with that, then integrate the design into a board and add an amplifier chip if needed for headphone use. 

Good audio is important to me, and I prefer to hear the world through my in ear monitors these days. Mee M6 Pro for anyone interested. My Pidock 400 takes HDMI audio from the Pi 400 and breaks it out to a headphone jack, so I've been quite spoiled by the set up so far. Not everyone is going to have one of them, and I want to see a headphone jack on the Pi 400. I'll put that task on the low priority list and focus on such luxury features after the base memory cart is working. I was curios as to what it would take to get a headphone jack on the PiCarts, and now I have a good idea. I don't have the skills to implement it yet, but I'll get there in time.