Hey Folks,
today, I would like to show you my Streamer-Project. Let me say, this is my first time beeing involved in such an project 
I was inspired by an publication in the German magazine “Make”, where a similar project was published (it looks like that project was also introduced here: Raspberry Streamer in Pioneer Case by @DieterS).
@DieterS created a really cool PowerSupply Control, but I wanted to keep my Raspi always online. But how to do that without wasting a lot of power for the linear power supply…? Thats why I decided to implement two separate power supplies, as main supply a linear one (THEL NT-50HQ-09) and as standby-supply a 12v Meanwell. My idea was, to supply the Pi with either the linear one or the standby-supply. To accomplish that, I added a power control based on an Arduino Uno, which controls several relays. So in standby-mode, the Pi keeps powered on via Meanwell and voltage regulator and in active-mode the Meanwell is cut-off via the relays and the linear power supply is switched on and begins providing the power.
The linear power supply also powers the 12.6" Touch Display and an external port, where the power of the DAC is connected to.
As the Arduino is controlling 2x 4-Relay-Boards, I can also loop through the 230V power for the amplifier. So this is how I could achieve, that when the Streamer is switched on, all depending devices like amp and DAC are also switched on and vice versa.
As my DAC does not support Hardware Volume control, I additionally created a small Plugin which controls the Volume of the DAC via IR when Volume in Volumio is changing. So I can control the volume via the DAC and also via Volumio.
The case was self-made with aluminium-profiles and lasercut acrylic sheets. All plastic-parts are custom 3D-printed.
This me as “noob” I am quite satisfied with the results I am sure, many things can be done better!
This are the main parts I used:
1x THEL NT-50HQ-09 Linear Power Supply
1x MeanWell NDR-120-12 (as stand-by supply)
1x Arduino Uno (controls the relays and the power switch, always powered on by Meanwell)
1x Arduino Nano (controls the IR-Signals, powered by RasPi via USB)
2x 4-Channel 12v Relays (always powered on by Meanwell)
1x 12.6" Touch Display 1920x515 (only powered on when active, via THEL)
1x RasperryPi 4 (Always on, either supplied by THEL or Meanwell)
The rest of my setup consists of this:
KEF LS50 Meta
KEF KC62 Subwoofer
RME Adi-2 DAC FS (also powered by THEL!)
AUDIOPHONICS LPA-S400ET (2x Purifi 400W)
Here are some pictures (and yes, cable-management is still work-in-progess 
):
Feel free to ask, if you have questions.
Best regards!
Michael