When trying to figure out what audio is the most current firmware for your iLink you can use the firmware that your current iLink is on to find out what it can go up to.
If your current firmware is 7.31.C1 or below then the lastest firmware for your iLink is 7.31.C1
If you current firmware is above 7.31.C1 then you are able to update to the latest firmware 7.38.A1 or above