Expert 140 Pro Sub Out without Preamp Ouput

[David A]

Biggest problem is that digiout is fixed output.

I think I can tackle that with the sub amp volume control, but that’s a good point.  

…

You can't tackle it with the sub "amp volume control". For a start it's not a volume control, it's a gain control.

The big problem, however, is that you're controlling overall volume with the Devialet's volume control. When you turn the volume on the Devialet up, you want the sub volume to also go up, and when you turn the volume on the Devialet down you want the sub volume to go down, and you want the sub volume to go up and down by the same amount as the Devialet's volume changes. If the digital output from the Devialet is fixed, then the sub doesn't change it's volume when you change the Devialet's volume. You may think you can compensate for that by adjusting the sub's gain control but let's say you increase the Devialet's volume by 2.5 dB, do you have a gain control on the sub that allows you to change the gain by an exact 2.5 dB? If you don't, then the balance between sub and your speakers gets slightly out of sync and the next time you change the volume on the Devialet and adjust the sub another error creeps in, and errors keep creeping in with every adjustment you make. It simply doesn't work unless you have a sub with a gain setting readout that allows 0.5 dB steps and you can ensure that the increase/decrease in gain setting matches exactly the increase/decrease in Devialet volume setting.

You need a variable level output that is controlled by the Devialet's volume control so volume of speakers and sub remain matched and you are adjusting both with the same volume control.