Does the player remember what level it set the volume at, or does it read it back from the kernel/DSP? If you try and change it through the player, it'll bring up the volume display, which would cause problems.

A proper volume adjustment system on the empeg would not mess with the ACTUAL VOLUME SETTING, it would modify the digital bitstream of the music, independently of the volume setting. That's what the current voladj compressor does.

A speed-controlled volume system would attenuate the digital bitstream's volume level when there is no ambient noise, then gradually lessen the attenuation as the ambient noise got louder. Finally, at full freeway speeds, there would be no attenuation and your player would be playing at the same volume as displayed by the volume knob indicator.

In this way, the volume knob would be setting your "desired apparrent volume" which is variable depending on your mood, and the speed-controlled-volume would be adjusting THAT to the background noise.