I am using a HK520 as my pre/pro. And the only way to control the volume from a remote location on the PA4000 is to install a keypad for every channel to be controlled. Which I haven't done.
I am able to control the volume using my 520 so I want to leave the PA4000 at its maximum volume. Unfortunately everytime the amp goes into standyby mode it defaults back to the factory setting for its maximum turn-on volume.
I am going to call HK again today and ask to speak to someone who has actually used the PA4000.
Are you sure it is the PA4000 you are having an issue with and not the 520? I have the 520 and there is an option in the Advanced Settings section of the OSD that allows you to customize the turn-on volume. You can either set it to turn on at a set volume (regardless of the volume it was set at the last time it was powered up) or you can have it use the same volume you last used.
I also have a PA2000 that I am using for the fronts. If it is similar to the 4000, there is no "turn-on volume" setting. There is a gain adjust (which I have set to max) and you use the receiver's volume control to set how loud the system is.