I am afraid that those boards will not play nice in the sandbox together - at least not as supplied and without further hacks.
The Amp+ and the DAC+ board share the following pins (see here GPIO usage):
GPIO 2 and 3 for configuration
GPIO 28 through 31 for the sound interface
For pins 28..31 they also explicitely state that:
You can’t use them for any ...
Actually, both would work and it is up to you. Either the DAC+ into your amp (using the RCA connector, red and white are the left and right channels), or the Digi+ for a digital connection to your DAC. Probably you wouldn't hear a difference, but who knows? If you want to use your DAC and have the input still free, use the Digi+. If you think you might need ...
Sounds like you're trying to build a crossover?
You can't, to the best of my knowledge, stack multiple HiFiBerry DACs for more outputs. Their help pages have an outline of which pins are used for what.
Personally, I'd go for an outboard crossover unit of some kind. It'll cost more, but stand a higher chance of success when you're already fighting against ...
I'd guess that both the HiFiBerry and the WiFi dongle together draw too much power. You should first try cold booting with the WiFi adapter alone, then the HiFi. Because the HiFi connects via pins, the Pi's likely to default to give all the power to it over USB. A stronger 5v wall adapter should help in this case. I'd guess it works when not cold ...
I suspect your problem here is the Hifiberry and LCD board are both intended to fit over the GPIOs "hat" style.
If the Hifiberry has a breakout on top, you should be able to put the LCD on that and use it without problems. As per the Adafruit page, that board only uses the I2C bus (plus power, presumably), and this can support multiple devices as long as ...
I recently faced a similar problem to this (using alsaequal with a USB sound card). It seems that Kodi is sensitive to the floating point input/output of that plugin, even if the hardware can handle it.
The solution is to explicitly slave the output of alsaequal to an lfloat plugin, and specify a non-float format (probably signed 16bit little endian). Then ...
If your code is working fine and you just need it to be run whenever after each boot process, you can create a systemd service:
Create a file called something like "/etc/systemd/system/pyscriptstarter.service" which should contain the following:
Description=Fancy Bash script to start fancy Python script
You certainly can approach it that way, but it's much harder. Using something like runeaudio or Volumio makes the process much easier. However, I understand why you would not want to. In this case, I think you can just install MPD (the music player daemon) Here is an article which details turning a Raspberry pi into a headless player: https://www....
Try the standard output, see if you like it. If you don't, get something more expensive.
Beyond that, any reply you'll get will be purely subjective; the objective measurements (SNR, frequency range, etc.) are all available at the respective spec sheets.
From the picture shown on Hifiberry's site we learn that it uses the PCM5122 Audio Stereo DAC with PCM Interface and Fixed Audio Processing. We also find a RC low pass connected between "something" (traces coming from under the PCM5122 itself) and the audio out RCA connectors. R6, C8 and R3, C7 form these low passes. So the external circuitry does not block ...
The P5 header has the following pins supporting PCM (high quality audio).
P5-03 GPIO28 PCM_CLK
P5-04 GPIO29 PCM_FS
P5-05 GPIO30 PCM_DIN
P5-06 GPIO31 PCM_DOUT
(All set to mode ALT2)
Those gpios are not available on the A+/B+/Pi2
The A+/B+/Pi2 have the following pins supporting PCM.
Pin 12 GPIO18 PCM_CLK
Pin 35 GPIO19 PCM_FS
Pin 38 GPIO20 PCM_DIN
Pin 40 ...