A relatively simple project this one but hopefully it's of interest to some. I've been using Pi based streamers for some time now and wanted to put it one into a neat looking box, with an internal power adapter and a front panel button to switch on / shut down the Pi gracefully, without risk of corruption of the SD Card. Total build cost was abut £415 -- 70% of that was casework and the RCA connectors.
First step was to desolder the RCA connectors from the top of the Hifiberry DAC+ HAT and solder-on wires to some massively over-engineered WBT RCA connectors. I chose these for aesthetics rather than any particular foo; some more sensibly priced ones would do the job just as well but I like them anyway. I may at sometime swap the DAC+ for a DAC+DSP, which would give the option of integrating room correction and possibly adaptive loudness control.
The box is from Metcase's Technomet range. It's intended as an instrument enclosure but it's nicely powder coated and all of the screws heads are hidden, except on the rear panel and the base. There is no heat sink but I think it's adequately ventilated for the Pi+DAC+PSU. Front and rear panels & the carrier plate for the Pi, HAT DAC & made by Schaeffer AG to my design (rear panel on order). I could maybe have attempted these myself at lower cost with some sheet aluminium but wanted a good quality powder coated finish and they've swaged on some earthing pillars blind, which would have been difficult for me to do.
A 15W/5V internal SMPS from Meanwell feeds an Audiophonics PI-SPC V2 power management module, controlled by the front panel mounted button. Many of the comparable builds I have seen on line have used regulated linear PSUs. One of these would have be more expensive, physically much larger and generate more heat, necessitating a larger enclosure. Archimango tested a Pi streamer with a wall-wart SMPS and found noise levels well below audible so I struggle to believe a linear power supply would make any meaningful improvement in sound quality.
All freeware: OS is stock Rapian Lite (Stretch), main streaming software is "Media Player" - a Java based DLNA compliant streamer with Linn's Openhome extensions so it can be controlled by Kinsky; it also includes Airplay. Raspotify makes it Spotify Connect compatible. One of the audio-centric distros like Volumio would have been less work but I like the flexibility & control of choosing packages individually.