I'm not sure whether you're going to be able to do exactly what you want or not - but let me explain exactly what's going on.
There is no way to actually configure or program the start-up volume on the Ego DACs.
The Ego DACs have an internal analog ladder network Volume control that can be accessed via metadata from the computer.
This was originally believed to be a cool feature but it turned out that only one or two Windows apps support it (and we didn't even know that any Apple apps did so).
In order to use this feature the player program has to support the option and SEND a command to the Ego DAC to set a certain level.
It simply allows the computer, or the player program, to remotely set the Volume on the DAC...
The DAC itself DOES NOT remember this setting... and the default startup setting is Full Volume.
(Otherwise, if it were set very low by a program that supported this option, there would be no way to raise the Volume using a program that did not.)
With most player programs, which don't support this method, the DAC is expected to deliver "full analog output Volume", and the level is controlled digitally.
And, in that case, most programs DO remember their previous Volume setting.
It seems surprising that programs that do recognize and support this option don't remember their previous default setting and apply it when they recognize the output device.
(But jRiver Media Center, which is the only current Windows program we know of that supports it, acts the exact same way.)
The only real way to avoid this is to use a different method of controlling the Volume.
(In which case the Volume will be controlled digitally and will be whatever each individual player program is set to.)
(jRiver Media Center, in Windows, actually offers BOTH options... as two different "Volume Control choices... although they are not labelled as such.)
I wish I could give you a better solution...
Because the internal Volume control is technically superior to a digital Volume control...
But this is one of the reasons we no longer bother to mention this feature much...
I use the Midi Setup app on MacOS to configure my little Ego. It works great and allows the Mac to set the bit rate and depth.
The only issue I have is that the default volume resets to 100% each time I plug it in. Sometimes I forget to change it and have had some painful experiences - the Emotiva headphones get really really loud!
Anyone know how to change the default output volume on startup?