Today I want to tell you about how to make useful the DIO part of an old but well old AP SYS2722/2522, which has only SPDIF I/O and quite useless nowadays. I have to use my AP with my USB DACs and SPDIF/TOSLINK I/O no use, hence, I losing convenient features of the AP2700 software(don't tell me that external sweep is ok too!). To make my AP "great again" I made a simple USB "SPDIF" optical bridge with 24/192 IN/OUT at CM6631A and default FW. See the attached schematic. Now I can make a fast and precise frequency response or THD+N vs frequency etc. After the external sweep, which drives me crazy, now I feel much better.