@phofman
Would the following setup work:
1st cs8421 with 24.576MHz crystal as MCLK source and I²S master output (32-bit@96kHz)
2nd, 3rd and 4th cs8421 with no OX as MCLK sink and I²S slave output with clock lines in parallel to 1st cs8421 and separate data lines
RPi5 in I²S slave mode...