I am messing around with a RPi 2 to use as a kind of black box to act as a piano sampler module so my sister can use my keyboard without having to learn how to use DAW's, also she says its a hassle to have to plug in her laptop every time she wants to play. (Piano player only, doesn't use any other instrument ever).
I tried using a USB DAC as suggested, but every time I test it out, I swear I can hear dropped notes and samples cutting out for the tiniest fractions of a second now and then.
The MIDI controller is USB MIDI, and my theory is that since RPi only has one US(B) bus, the sound card and controller are competing for access in certain very specific conditions that degrades performance in a noticeable way, so I am going to try using a PCM5122 DAC using the I2S bus via the GPIO pins (GPIO 18 - 21, except 20 which is input), but I'm not sure which pins are free and which ones are not in the standard image. In fact, should I even be assuming the standard dev are on the usual pins, or are they reassigned in samplerbox?
Oh also GPIO 17 is used for the IR receiver on the HAT I have, though I can't think of any uses for that.
So TLDR; I'd be very much obliged if anyone can point me to a reference doc or part of the source that lists the pin assignments, or if there is a way to find out in the shell.
Thanks in advance,