How to power raspberry pi via Adafruit 20w Amp?

Hi

I am building a Raspberry Pi speaker. I’m using gan old Raspberry Pi Model B (revision 2.0) which is already running Shareport Sync.

I’d like to hook up my Raspberry Pi to the Adafruit Stereo 20W Class D Audio Amplifier - MAX9744, but also have them utilising the same power supply. From what I’ve read online this is possible, but I am unsure how exactly to do this. I have some thoughts, and am hoping someone can tell me if I’m wrong - here are the steps I think are needed:

Connect MAX9744 Amp to power supply 12V DC 5A (e.g. https://core-electronics.com.au/12v-5a-switching-power-supply-45158.html)

Wire the VDD and GND pins on the MAX9744 Amp to a step down regulator:

or

The step down regulator will in turn be wired to a micro USB plug (https://core-electronics.com.au/usb-diy-connector-shell-type-micro-b-plug.html) which will then power the Raspberry Pi (with protections still in place)

Questions:

Will this set up work?

Which step down regulator is best? The voltage regulator sounds less efficient, and I read it may cause heat. It only has 1.5A as well. Is this enough for the Pi? The buck convertor seems to be more efficient, but has only 1A - so same question for whether this will power the Pi?

I am planning to use the MAX9744 Amp in analog mode. But want to check that if I set the Amp at some max volume level using the the potentiometer, I will still be able to control the volume at the source (i.e. from the Pi running over AirPlay)?

Cheers

If you don’t have one lieing around, don’t forget the IEC power cable for the power supply.

Consider this DC-DC converter. Capable of the 3A recommended for the RPi.

Perhaps a splitter cable to split the output of the power supply, and a couple of barrel Jack’s?

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