Hi janvda,
Thank you for the reply. Sounds very reasonable, that 12 v constant is required to keep the amplifier on.
Using usb as a trigger is a good idea, but it requires a device with usb output, and my stream-9 does not have that.
However, when inspecting the stream-9 closely, I discovered that it actually has a trigger output!
That may be used to trigger the poweramp. It would be preferred, if the preamp or dac was the trigger, but there are no trigger out on them.