In a related question, how long before the 2200 M-Blocks enter Standby mode after a Model 990 is put into Standby mode?

The manual states "a few minutes after the audio signal stops," but I put the 990 in Standby mode and a few minutes later lights were still green on my new pair of 2200's. They're set up correctly, per the manual: each 2200 has its power switch in the On position and the Trigger Mode Switch set to Music.