This is confusing. Although I think I have the answer I need, which is in bold. I would like clarification. I understand that volume can be controlled in your music player via software, that should be obvious. I was wondering if we have any control over the output levels of the DAC directly through the OS. (ie. my odac can be controlled using the volume keys on my keyboard) From what Doc wrote above, it looks like the answer to what I'm asking is no. I can assume a constant output then (when all software volume is at 100%), in all situations, correct?
Good to see the first run of DACs are almost out the door, I'm eagerly awaiting to hear people's responses.
Whether using the volume control on the keyboard will affect the output volume depends on the software player and how it is routed. Most OSs include some form of OS mixer, if your player routes the audio through the OS sound path then using the keys WILL change the volume. This can be actually done in several ways depending on the OS and DAC driver. In some cases pressing the keys changes the volume of the OS mixer, which does the volume change, OR the software player can register itself to receive the volume control events and do the volume control in the player, OR the DAC driver can regitser the DAC to receive the volume control events.
In the case of a USB DAC the DAC can tell the USB driver whether it responds to volume control events. In the BH DAC case the DAC itself does not respond to volume control events, so it does not register to receive them, thus pressing the keys will either cause the player to do the volume control, or in the default case the OS mixer does the volume control.
This is assuming the player is sending the data through the OS audio path which includes the mixer. For example if you are on Windows and using a player which is setup to use ASIO, it will NOT send the data through the OS mixer. So if the player registers itself to receive volume control events then it can do the volume control. If it does not so register itself then using the keys will not affect the volume.
So the upshot is that more than likely the volume keys will work, but there is a chance they will not depending on the player you are using and how it has been configured.
I know not a simple answer, but that is the way it is today.
John S.