I want to try to make a prototype of hardware audio DSP module, so I need both audio input and output. RPi 3B only has one, and the quality is poor, so I'd better to connect audio IO by myself. However, it seems RPi 3B only have one group of I2S interface present in GPIO pins. So which board can I use for two I2S interfaces?
By the way, I know the simplest way is to connect a sound card on USB (and I have a SoundBlaster X), but it's too different from what I want, as it's quite unlikely to use an extra USB sound card in a product-like thing.