If your unit has S/PDIF connectors (older units): version 1.02 R228
If your unit has no S/PDIF connectors (newer units): version 1.03 R244
You can check what version is loaded when powering on the unit.
Note: If you have a newer version without S/PDIF connections, they all come out from factory wit the latest version possible, and are consequently up to date. Only older models could need to be updated.