MEASUREMENTS: ODROID-C2 with Volumio 2, and USB digital music streaming.

ODROID-C2 & unused "Fujifilm" 5V 1.0A wallwart ready for testing...

For those following along, you're recall back in March, I purchased a Hardkernel ODROID-C2 Linux-based credit-card sized single-board computer; the hardware described in my preview. I loaded up and customized the machine with Volumio 2 (RC1) a couple weeks back. And now as promised, I'll be showing some measurements using this machine with my TEAC UD-501 DAC. (Note that there has been a new Volumio image update since my last post. The current version is "VolumioRC1-fix-2016-05-03-odroidc2.zip" found here. Only fixed some boot issues apparently.)

Before I begin, let's discuss what we're trying to figure out objectively here... It has been claimed by some that the USB interface (which the ODROID will be streaming through to the DAC) can be "bad". Supposedly, it's electrically "noisy" (of course a noisy fan and spinning hard drives are also very bad). And, this is especially "bad" with computer audio because computers are electrically noisy devices and will end up polluting the output from your DAC. Hence, by this reckoning, a general-purpose computer isn't supposedly a good thing to have doing high-fidelity audio duties. Furthermore, it has been surmised by some that power supplies can be problematic. Specifically, an inexpensive switch-mode power supply (like the one in the picture above) can be noisy and again, will have deleterious effects on the sound quality.

It has been said that devices like the recently released Sonore microRendu among more fancy audio streamers like the Auralic Aries line of devices can "sound" better because they reportedly take into account the various sources of noise and supposedly have optimized hardware/software. True or not, the price of such "audiophile" grade devices can be rather substantial especially when it's a device without internal storage and acts as a digital conduit to feed a DAC.

SET-UP: Low Power Linux Audio Player (ODROID-C2 & Volumio 2)

As you know from a few weeks back, I got myself one of these little single-board computers (SBC) - the Hardkernel ODROID-C2 - and posted a PREVIEW on it. As described in that article, I had flashed a copy of Volumio 2 "Release Candidate" (0.861RC1) to my SDHC card and have been streaming music to my TEAC UD-501 DAC in the music room for the last while.

Originally, I was going to publish both the contents in this post as well as measurements but it quickly became obvious that this was going to be too unwieldy (plus the day job got very busy)! As such, let me talk about the basics of the setup here today along with a few changes you might want to try if you're streaming from one of these Linux-based network machines. Then later, we'll get to the measurements...

Note that although I'll obviously be specifically addressing the ODROID-C2 I have here, the software is portable and at present, the good folks at Volumio have software images for many low-power computers including: Raspberry Pi, Beaglebone Black, Cubox, ODROID-C1+, etc... Just check their site to see if your machine is supported with a ready-to-use OS/app image. I've been informed that RuneAudio will also have ODROID-C2 support ahead (maybe as early as this weekend), so keep an eye on that one as well!

PREVIEW: ODROID-C2 Single-Board Computer... [And an obligatory MQA addendum.]

Over the last year, every once awhile someone will come and ask me when I was going to try out a Raspberry Pi as a streaming replacement for my Squeezebox systems... Certainly I've been looking around and while I was relaxing in Puerto Vallarta a few weeks back, I decided to leisurely check online the varieties of these low-cost single-board computers (SBCs). Here's a pretty good list of recent SBCs on the market to get a feel of what's out there in early 2016.

Without a doubt, the Raspberry Pi computers are the current reigning champions in popularity. They announced 5 million units sold back in early 2015. The recently released Raspberry Pi 3 looks excellent. Plenty of support, reasonably fast quad-core Broadcom BCM2837 64-bit ARMv8 1.2GHz, decent but not impressive 1GB RAM, OK 10/100Mbps ethernet, and convenient wireless 802.11n WiFi with Bluetooth 4.1. The list price should only be about US$35 for one of these but due to worldwide shortage, there's a bit of a markup currently (very common supply-demand issue of course).

But looking around, another little computer caught my attention - the US$40 ODROID-C2 from Hardkernel, a South Korean company. This was just released in March 2016. I was able to get it here in Canada from Diigiit Robotics but I see that they're now out of stock and like the Pi 3, prices have become elevated. Here's the block diagram for the C2:

All technical details including schematics can be found here.

As you can see, it's a reasonably powerful little unit which easily can outrace the Pi 3 computationally (some benchmarks here compared to Pi 3). Quad-core Amlogic S905 CPU with 64-bit Cortex-A53's running at 2GHz, 2GB of DDR3 RAM, Gigabit ethernet, and a video subsystem capable of HDMI 2.0 4K/60fps output and hardware decoding for H.265 (750MHz Mali-450 "pentacore" GPU). Unlike the Pi 3, this unit does not have built-in wireless communications. Micro-SD card (supports UHS-1 speed) can be used or faster e.MMC 5.0 (400MB/s interface) module for flash storage. There's also an IR receiver built-in for remote control of features like volume adjustment.

So I figured... Why not? Let's get one of these little guys with the goal being to run a simple Volumio streamer out of it (I think we'll be seeing RuneAudio on this device soon also). Here's what I got:

The ODROID-C2 with clear plastic case. Note how small this computer is - about the form factor of my Costco card :-). Around the same size for the Raspberry Pi...