The Fives Volume Control with USB

I recently purchased The Fives.  So far, I love them!  I usually only use the AUX input as I use various inputs from a submixer.  I would love it if the volume from the USB option controlled the volume for all other inputs.  What this would allow, would be controlling volume from my PC by controlling the playback device volume.  I've previously been doing this with other speakers that have USB and Line-in.  This way, I could still have it on AUX, but control the volume from peripherals on my PC instead of using a remote.