hello sandston - i've got a project in the works to do the same. After giving up streaming via NAS due to noise and dropped signals, here's what some research came up with:
Design Criteria
It's tiny
It lives by the Stereo (connects to a DAC and Integrated Amp)
It holds all music, in all formats (m4a, mp3, flac, wav, ogg, etc)
It plays 24bit/192kHz without any downsampling - HD Audio Codec (Realtek ALC269 or better)
It syncs wirelessly with other machines (i.e. for running back-ups, managing additions, editing the library), preferably via WiFi rather than bluetooth. (802.11 b/g/n)
DNLA compliant
The operation is controlled via remote, from another machine, Android phone, etc. (PC, Mac or other) - WiFi (Bluetooth could be offered as an option)
It uses an already existing free music app for management, play, remote control, etc - e.g. musicbee, foobar2000, vlc, etc so users can keep using what they like. Nothing bespoke.
It offers 2+1 USB (two 3.1 type A and one type C) for connection to an external DVD/CD burner and whatever other device (USB key, external drive, phone, iPod, etc)
TosLink S/PDIF for connecting to a DAC (or DAC/Amp). Option for mini-TosLink/3.5 audio jack out.
Coaxial option for connection to a DAC (or DAC/Amp).
Low or no noise components, so SSD drives. Passive cooling.
Has capacity for 1Tb memory. These should be easy to swap out, so accessible
Includes LAN port for hardwired net connectivity - Network RJ-45 10/100/1000 Mbps ethernet
Low power (it'll be on all the time), at or below 25W
Video port is an option, but not critical. HDMI?
Option 01 - Micro VortexBox http://shop.smallgreencomputer.com/Micro-VortexBox-vbMicro.htm ($760usd)
Option 02 - Dedicated Laptop
Chromebook, Lenovo 100S - http://shop.lenovo.com/ca/en/laptops/lenovo/chromebook-series/100s-chromebook/#tab-tech_specs 32Gb/4Gb RAM $299
Lenovo Ideapad 100 - http://shop.lenovo.com/ca/en/laptops/ideapad/100-series/100-14-inch/ 500Gb 2Gb $399
needs USB to S/PDIF (e.g.: M2Tech - HIFACE-TWO - Hi-End SPDIF Output Interface -BNC Version)
Western Digital My Passport 1 TB USB 3.0 Portable Hard Drive - $120
Option 03 - Custom Unit using Ultra-Compact PC Kit
Gigabyte Brix, model: GB-BXCEH-2955 $170
http://www.gigabyte.com/products/product-page.aspx?pid=4860#ovIntel Celeron 2955u 1.4GHz
Supports 2.5” thickness 7.0/9.5mm Hard Drives (1 x 6Gbps SATA3)
Ultra compact PC design at only 0.52L
1 x mSATA SSD Slot
2 x SO-DIMM DDR3L Slots (1333/1600 MHz), 16GB max RAM
IEEE 802.11 b/g/n Wi-Fi/Bluetooth 4.0 Mini-PCIe card
HDMI Plus Mini DisplayPort Outputs (supports dual displays)
Intel®HD Graphics
4 x USB 3.0
Gigabit LAN Realtek RTL8111G
Headphone jack with S/PDIF, Realtek ALC269 (All DACs supports 44.1/48/96/192kHz sample rate, SPDIF-OUT support 16/20/24-bit format and 32/44.1/48/88.2/96/192kHz rate)
VESA Mounting bracket
Dimensions: 42.8 mm x 107.6 mm x 114.4 mm (1.69" x 4.24" x 4.5")
Zotac ZBOX CI323 NANO-Plus Barebone Mini PC
http://www.canadacomputers.com/
https://www.zotac.com/ca/product/mini_pcs/zbox-ci323-nano-windows-10-home#spec
Intel Processor Intel N3150 quad-core 1.6GHz, up to 2.08GHz (better chip than Gigabyte Brix Celeron 2955u )
2GB DDR3L (two slots up to 8GB, one slot occupied)
Wireless 802.11ac + Bluetooth 4.0
Ethernet 2x 10/100/1000Mbps with antenna
Onboard 32GB M.2 SATA SSD
1 x 2.5-inch SATA SSD/HDD (Samsung 850 Pro Series Internal SSD, 2.5-Inch, 1TB SATA III, 3-D Vertical or 500Gb for $218)
CIR Infrared Port
Audio: Stereo output, Lossless Bitstream via HDMI, Combo mini-optical S/PDIF / analog stereo
USB: 1 x USB 3.0 type-C (front), 2 x USB 3.0 (1 front, 1 back), 2 x USB 2.0 (back)
Card Reader: 3-in-1 (SD/SDHC/SDXC)
127mm x 127mm x 45mm
Option 4
Raspberry Pi 2 B +HiFiBerry Digi+
https://www.hifiberry.com/digiplus/ $40 (HiFiBerry Digi+ transformer version)
https://www.raspberrypi.org/products/raspberry-pi-2-model-b/ 4 USB ports, HDMI, Ethernet, 3.5mm Audio, Micro SD card slot, 1Gb Ram, $60
https://www.raspberrypi.org/products/usb-wifi-dongle/, Edimax 150 Mbps Wireless 11n Nano Size USB Adapter (EW-7811UnR2), $17
Raspberry Pi Western Digital PiDrive 1TB Hard Drive Kit Now Available For $80Western Digital PiDrive Kit, $80
Micro SD Card (32Gb minimum, SanDisk Ulta $16)
Samsung 850 Pro Series Internal SSD, 2.5-Inch, 1TB SATA III, 3-D Vertical, $612
Total: $40 + $60 + $17 + $80 + $16 = $213 + memory ($612) = $825
Add-ons - Add-On Boards and Modules within Raspberry Pi - MCM Electronics Category
Software
RaspyFi - Pi never sounded so good!
https://www.hifiberry.com/guides/hifiberry-installer/ (https://www.hifiberry.com/guides/setting-up-volumio-to-get-great-audio/)
https://volumio.org (audio optimized alternative to Raspbian) https://volumio.org/get-started/ for set-up instructions
http://moodeaudio.org/ Audio player for Raspberry Pi
SyncMe Wireless for Android devices.
MediaMonkey can play 24/192 with ASIO plug-in
PINE A64+ Home - PINE 64
64bit Quad Core ARM A53 1.2GHz CPU
Dual Core Mali 400-MP2 GPU
2GB DDR3 SDRAM
MicroSD Slot Supports up to 256GB
10/100/1000 MB Ethernet port
2 x USB 2.0 host
4K x 2K HDMI port
3.5mm Stereo Output mini-jack with Microphone Support
Muti-Channel Audio output through HDMI
Real-Time Clock capability built in
Built in 3.7V Lithium battery charging circuit
5 Megapixel Camera Port
4 lanes MIPI video Port
Touch Panel Port Included As yet, there's no plug-in like the HiFiBerry, but that couldn't be far behind.
Hope that's not too much... The last few options would require some work to set up, but could be made quite lean if all they're doing is sending music to a DAC.