FreeDSP (ADAU1701) isn't working - what is the issue?
It appeared to be an EEPROM issue.

In the user guide, "Transfer your program using an Arduino programmer" part is wrong. SigmaStudio's hex file isn't actually a hex file, it's rather a plain text file of comma separated hexadecimal numbers:

0x00 , 0x04 , 0xFF , 0x00 , 
0x0c , 0xC2 , 0xA0 , 0x01 ,
...


So in order to transfer your firmware to EEPROM, this file should first be converted to a real binary file.



As for me, I ended up using a separate EEPROM writer. The writer supported only Intel hex formatted files, so I used this program for conversion.