Inrush current into the power supply caps is what the supply can deliver.
Could be a lot more than 2Amp. You can only measure that with a scope, not with a slow DMM.
Current draw of a class-D amplifier depends on supply voltage and speaker impedance.
With 8-ohm satellite speakers (not including woofer), and a 24volt supply, that could already be ~4Amp full blast.
I expect you need a 24volt/10A supply for that board.
How are the RPI/Nano powered.
Should be a separate supply, or that buck supply should be buffered with a cap and diode between the two supplies.
I was suspecting that what I caught, even after setting the DMM to Fast Mode, was probably not the full spike. I attached the image of the screen showing my measurement. It shows just under 2A but in a previous measurement it clearly reached 2A. I have a scope but I don’t have a current probe. I guess I could likely figure it out using a large low ohm resistor but have not done so yet.
The speakers are 4 ohms, and I assume the sub as well (I can’t see the back of it). I do not need anywhere close to full power as this is a two player table top arcade. The only reason I went with this amplifier was that it could be powered at 12V and it was 2.1. I had an itch to add a sub to my arcade to see how it would sound. Well… if I can the arcade not to reboot, I will keep it as it sounds cool (the bass…).
The power supply I used in a similar arcade, and chose to use again, is the Mean Well RD-65A. It has 2 rails: 12V 3A (~4A max) and 5V 6A (~8A max). With a smaller 10W stereo amp it works great…
One of the images attached shows my spartan layout inside the arcade. No space for another power supply unless I redo it all.
The LED marquee is powered at 12V and it draws 1A or less at the brightness level it is set at (50% or so via PWM).
The power amp is powered by the 12V rail and my measurements showed it generally was between 300 and 800mA at the desired volume. I tried to blast it as loud as it would go and never saw it exceed 1.5A but I may be missing fast spikes. I was using test sounds to drive the amp.
The RGB LED arcade buttons are all powered at 5V. The power requirement is low but I don’t know the exact amount. There are 20 RGB LED buttons with a small control board. They could, but rarely are, all turned on.
The Arduino Nano is on a shield that require 7 to 12V. If I power it at 12V the Arduino’s regulator gets hot and eventually burns out. I have an LM2596 board that reduces the 12V to 8V and is capable of 3A. There are 2 regulators on the Arduino shield that provide the 3.3V and 5V for the things powered by the shield.
The Raspberry Pi 4 is powered by the 5V rail. The rail is set to 5.2V which I believe is the upper limit of the USB bus that is directly connected to the RPI power input. The RPI is sitting on top of a USB3 SSD interface in case you wonder. I have 500GB worth of storage space.