Hi, I'm relatively new to hard drive audio, but want to give a nod to the Raspberry Pi v2, run with Kodi (via OpenELEC). This gets me an audio source better than any I've used so far.
My first setup using a hard drive library was with the Western Digital "WDTV Live SMP" media player along with a USB hard drive (helpful note: make sure this has its own power adapter!). That worked somewhat ok for a year or so, but had problems -- it would crash from time to time, had buggy software (and very slow to zero reaction from the company to fix it), and I had to have a directly connected TV screen showing to effectively use it. I want to use my setup in audio-only mode, even from power-up, and particularly when selecting tracks, and big lit-up screens are distracting.
So, I tried one of the inexpensive Android media players ("Keedox Dual Core Android 4.2 Smart TV Box XBMC Media Player") and a $70 Android tablet for remote control. I wanted it to start up in XBMC (now called 'Kodi') so I could play music without a big distracting TV screen on the wall, so I found an app called 'XBMC Launcher'. The tablet used a (very nice) app called 'YATSE' to give remote control of the Android program. The Keedox was running a modified Vidon version of Android. Getting that all to work reasonably required trying different versions of the Vidon Android and some help from the author of XBMC Launcher. And still, the Keedox box would crash unpredictably and it took upwards of 7 seconds for a newly selected track to start playing! And using it all for listening to internet radio stations was not very convenient.
I read about the new Raspberry Pi v2 boards. They sell for all of $35 (or about $69 with case, power supply, SD card and wireless stick from MCM Electronics). So I gave it a try. And I can say that this is 'it'. RasPi runs versions of Linux (open source!) and runs surprisingly fast for a tiny, cold-operating board. I downloaded a Linux version (free) called OpenELEC, which is optimized particularly for the XBMC/Kodi application - it boots up running Kodi, so no main screen required. It interacts with the YATSE remote like a charm, hasn't crashed yet, starts music playing within about a second of selecting, controls the USB hard drive like a charm. And I can select and play internet radio, as well as my FLAC music collection, right from my tablet at my chair.
Just in case anyone else out there is looking for a way to get FLAC audio from hard drive to receiver, without a computer, and without an attached TV display. And for not much $$ at all. And required just an afternoon to get it all set up.