So, background: I’m thinking about getting a Pi Zero with a pHAT DAC to solve a minor problem with my car stereo - while connected via bluetooth (to my Android phone) it won’t display the current media playing or let me use the steering wheel controls. There’s a USB drive and the stereo system will read songs from there, but it would be convenient if it worked for podcasts on my phone as well. But the stereo is old enough to support the Apple Accessory Protocol, so my (hopeful) solution is to wire a Pi Zero W to connect to the Android phone as a bluetooth speaker, to the stereo as an iPod (as a USB gadget + 3.5mm out), and bridge the two with both audio and data.
My actual question is if the pHAT DAC will work without an amp. My understanding is that headphones won’t work with the pHAT DAC because it won’t amplify the signal, but powered speakers will work without a separate amp. If that’s the case, my car speakers should accept the unamplified signal in the AUX port and output audio just fine. Unless the stereo system is expecting an amplified signal since it’s supposed to take a headphone line-out? I don’t actually know, so I’m hoping somebody that knows more about electronics and sound system can at least give me a definite “yes it will work” or definite “no it will not work” or a general “it’s impossible to tell without knowing more about your stereo system” (in which case I’ll stay on the safe side and get a mini amp or another pHAT with an amp).
Secondarily, I’ve done some soldering (rewiring a “greeting card circuit” to activate when a box opens), but this would be my first project of this kind. As I understand it, assuming it works as a USB gadget and I can program it to fake an iPod, I will need the following hardware:
- Raspberry Pi Zero W
- pHAT DAC
- USB Male breakout and wires to combine the power and data into a USB Male plug
- 3.5mm male-to-male cable
- A male header for the Pi
- A female header for the pHAT
- Some kind of case to protect all this and hold it together
Is there anything obvious I’m missing? Is this the kind of project that would warrant a heatsink, for example?
Thanks in advance.