Related: Raspberry Pi 3 audio input?
I need to be able to input several jack microphones (minimum 2, more could prove useful) to my raspberry, to do some audio processing (between all inputs), and output to a speaker. To make things worse, I also require a low processing latency between microphones and speaker (2ms would be good, and ~6ms is too much).
I've found a list of possible expansion boards that would allow me to do this: https://elinux.org/index.php?title=RPi_Expansion_Boards#Sound Specifically the audio injector stereo sound card seems to have 2 inputs, and the audio injector octo sound card has more than enough. I can't find the documentation for any of these cards on how much latency they may have, however.
The other sound cards on the list seem to have only 1 audio input.
I'd like to know if there are any other expansion cards (for the PI 3B+) or the latency of the cards I mentioned.
edit: some extra info from "Is Raspberry PI 2 B suitable for a real-time audio effects application?" mentions operating system has a big impact on this delay. If so- are there any OSes that are better for this purpose, or would it be better to do kernel coding as that thread suggests? (and is it accesible/easy to do so)
edit: after some more research, a better option seems to be beaglebone with a "bela" extension on top, as it has a custom operating system that allows for the sound to be processed separately, thus reducing latency.