Thanks Martialovid, I had been using a stereo trigger wire for my Adcom set until the Adcom Preamp freezed more and more often, when it did, there is no volume or any key control neither with front panel switch or remote except using front panel switch to turn off unit, then it would come on blank screen with no sound, no control, sometime later you might be able to turn it on again normally but only lasted a little while then the same thing happened again.
I bought the 990 to replace it. The stereo trigger did turn on the Adcom GFA-7500, but the sound came out from speakers are so tiny almost impossible to hear. Last night I tested with the trigger wire left between 990 and GFA-7500, but put the speaker wires and the coaxial out from 990 back to the Adcom GTP-750 preamp (with all units off), when I turned on the 990, the trigger turned on the Amp and after the Adcom is on, sound came out OK (Adcom Preamp still work sometime). That means trigger from 990 can turn on the Amp. I will still try to find a mono trigger wire to try though may not be the problem.
I don't quite know what you mean press the tuner button then the video buttons to change from tuner to my inputs, I did try it but no difference. Could you be more specific?