Same here. I just received my 770 yesterday, and presumably it's among the last of that line. The power button itself glows kind of a sickly greenish as long as the rear power switch is on and the green button is in. It unfortunately does not reflect the state of the trigger input.

I used to have a 950 preamp before I got the 990, and it didn't work the same way. The 950 had an LED below the green power button that lit up when the unit was in standby, went off when the unit was on, and blinked when muted. I wonder when/why the decision was made to make the 770 have a glowing button instead of an LED. I could have sworn the original 770's had a visible LED.