ok, found this:
As described below, firmware version 3.11 was released on June 13 and addressed a single issue (the subwoofer trim bug reported a week or so after version 3.10 was released). With this firmware update, the subwoofer trim behaves properly. Around the same time this firmware update was released, Outlaw provided a bit of clarification on the version numbers displayed by different Model 990's. (Pressing "SELECT" and "INPUT" on the front panel at the same time while the unit is in standby displays the version number, but be careful because "SELECT" and "MENU" will reset the unit to factory defaults.) The version number is displayed as "Version x.xx xx" with the first set of numbers ("x.xx") representing the firmware version (3.10 for the May 21 release, for example) and the second set of numbers (" xx") reflecting the build date of the particular 990 being updated. That second set of numbers has appeared most often as either "03" or "04".
The only problem...there is no "select" button
on the front panel!!