No need to turn on the tv, Just hit the Test button on the remote and "Test Off" will appear on the front window of the 990. Then after punching the enter button twice you can toggle between the left and right mains when in stereo mode or scroll through all speakers when in dolby mode and make adjustments to the settings. But, you must hit the enter button to trim the volume for any speaker then, once you have made your change, hit it again to make them permanent and enable you to move on to the next speaker. If you want to time using the test tones, hit the test button then hit enter once and then hit the up arrow above the enter button on the remote. From there, use the side arrows to toggle between the mains in stereo around all the speakers when in dolby movie or music.

The manual gives instructions on this. It just bums me out that you can't trim the sub while in stereo mode. From what I can tell, you have to go into dolby first to do that.