So, which of these gave you the best sound, if paired with a RPi?
If used directly to Rpi is will come down to personal preference. 9018K2M was a little fussy the last time I tried with Rpi (software, Rune, squeezelite)
How well the Rpi (squeezelite/MPD) works will most determine quality. A reclocker would be the expensive option to increase performance. (If Kali, DAC needs to be slave)
A is more convenient as it only needs 5V, the cleaner the better. Although it is not a plug-over GPIO pins board. (needs 6 dupont wires)
D needs 4 extra clean supplies. (+12, -12V, +3.3V, 3.3V)
I rather like the sound of the 9018K2M, if used with USB i2s and X86 PC the added benefit will be DSD64/128.
You could also opt for USB (i2s chipset) to Rpi but this may produce buffering due to USB bandwidth problems.
Compared to the IQaudio Pi-DAC+ (BB/TI 5102), I prefer the sound of A, then D.
The quality of the power to the Rpi will be a factor.