Just opened my new $2300 surface book 2 and found out that the Power and Volume buttons (on top of the display) don't work ! The keyboard volume up/down buttons work. And, I can turn ON the Surface Book by using the Power button. I can't put it to sleep or turn it off using the Power Button. I did do the 2-button reboot and that did not fix it. 0.3125. You could improve a little : if the level is already at max, pressing the up button will not change the value (simlilarly at min) You could set the system volume to 0.9375 or 0.0625 when at max or at min (that would be minimal disturbance for user, but not perfect) (values are coded on 4 bits, 16 values between 0 and 1) This gets it done: It takes a 12volt trigger from the preamp. It powers up the main PSUs and switches the speakers on after a few seconds wait. When the preamp powers down the power amp waits 5 minutes and then disconnects the speakers before shutting the main PSUs down. No clicks, bangs or anything else untoward. Mine started the same exact thing last night. 4 days out of the box, power button and volume down stopped working. Will be replacing, not trying to patch up with a "fix" this early on. Also, all the apps on the new phone are the same apps from my HTC one that I used for 2.5 years without problems. The app adds a shortcut panel for a variety of essential functions like power, volume up and down, brightness adjustment, multitasking, and more. On phones with Android 9 Pie or higher, Android Accessibility Suite comes pre-installed in Settings> Accessibility. The preamp is a Tortuga LDR DIY version. Raising the volume with the remote just produces a signal with a beeping light but gives no indication what the level is set at. I ended up with the power amp set at 90% of full volume. With only 2 watts to work with I ran out of power when the volume at the power amp was set at 65%. .

volume up volume down power