I discovered how to check the version of firmware your 990 has. I'm curious to see what versions are out there, since I've seen some differences in behavior of the serial protocol between my unit and kwoodrow's unit.

If you put the unit in standby (yellow LED lit), hold down enter (center of the navigation arrows) on the front panel and tap "input" you'll get a version up on the display. WARNING: Be careful not to hit enter and menu, as this will reset the 990 and you will lose your settings.

Mine is VER 3.00 03