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See below for the documentation. What I have done on my fanless PC is to separate IRQ (interrupt) activity from the cores which handle mpd and sox, to prevent unnecessary context switching. Worth the trouble. https://cs.uwaterloo.ca/~brecht/servers/apic/SMP-affinity.txt

@Dynobot: I've used cpusets on my fanless PC, but it's not included in the standard Raspbian kernel. I think the result is about the same. I've also looked at IRQ balancing, but to no avail either. Anyone else who has tried this? @rikhav: you can either run the statement directly from the command line, or put it in the init script. I don't know where Moode stores these scripts, but under Raspbian they're in /etc/init.d So in the "mpd_start ()" section in /etc/init.d/mpd, replace the original command line by: start-stop-daemon --start --quiet --oknodo --pidfile "$PIDFILE" \ --startas "/usr/bin/taskset" -- -c 1 $DAEMON $MPD_OPTS "$MPDCONF"

Last week I ordered a Raspberry Pi 2 and a Hifiberry Digi+ board to go with it (the version with the output transformer because I'm using the coaxial output). For the money I wanted to give it a shot, but this little device really blew me away. I've installed the last version of Raspbian in a headless setup, stripped down and running just MPD and SoX. It needs a little tweaking and some help from around the internet, but it's worth the trouble. You know it sounds good when you suddenly have to turn up the volume to make up for all the noise you're suddenly missing. I never knew there was so much silence hidden in the tracks I've been listening to for years Anyway, to get the best results here's what I did: - Get rid of the ethernet connection in favor of a wifi dongle. It makes a huge difference. Something that was pointed out already by the creator of the Hifiberry: Tracking down noise sources on a Raspberry Pi | Crazy Audio - Get a proper power supply. I went from a cheap no-name charger to an Apple iPad charger, to the SBooster linear power supply which I had been using on my MF V-Link. I just needed a connector to convert from USB B to micro-USB. Each power supply gave better results. - Downclocked the Raspberry by adding the following lines to /boot/config.txt. The improvements were subtle though arm_freq=400 sdram_freq=250 core_freq=250 - Using taskset to assign the mpd process to its own CPU core: taskset -c -p 1 $(pidof mpd) - Using SoX to upsample my 44/16 FLAC files to 24/96, while running multi-threaded on the two remaining cores. Here's the configuration in my mpd.conf: audio_output { type "pipe" name "Hifiberry Digi+ SoX 24/96" format "44100:32:2" command "taskset -c 2,3 sox --multi-threaded -traw -r44100 -esi -b32 -c2 - -esi -b24 -c2 -talsa hw:0,0 rate -v -s -L -a 96000 2>/dev/null" } I'm very pleased with this setup and hadn't thought this was possible for so little money. I think the Raspberry will replace the MF V-Link and fanless PC. Of course, I'm interested in hearing your results. Please share them below.

It's a Duson PA-100. Quite an old model, but the sound is still excellent. See the link below for some more info. https://sites.google.com/site/dusonhighend/geintegreerde-versterkers/duson-pa-100

Maybe a bit off topic, but did you turn off hyperthreading and CPU frequency scaling features such as EIST (through the BIOS) or other powersaving features? It made a huge difference in my setup.

Thanks for your response. The mainboard I use is of Thin Mini-ITX format and has direct 19V DC input, so no need for a converter. The PSU is rated 100W, which is more than enough in my case.

One more picture of my current setup. The PSU is in the cabinet, next to the NAS. I normally have a panel in front of it to tidy up a bit.

Just like many of you, I have also been looking at an affordable linear power supply that would meet my needs. I stumbled upon this newly available PSU from HDPLEX: HDPLEX Fanless Linear Power Supply for PC Audio and CE device It can be used to power two devices simultaneously, my main audio player (19V) and NAS (12V), and is affordable as well. Because I live in Europe, I saw that they also send from Germany, which saves me on import duty and taxes. Combined with a favorable USD to EUR rate, I decided to order one. This week the PSU arrived and I put it to the test. I have listened to it for a couple of hours now, but the improvements where spotted easily. Because I already use a separate power supply on my USB-S/PDIF converter, I did not expect the effects to be big, but it turned out to be a very welcome addition to my setup. As noticed in other threads, I found that the linear PSU improved the sound on imaging, transients, detail and bass. Especially on live recordings, there is a huge improvement in detail and realism. Overall I am very pleased. If you live in Europe like me, this PSU might be a good option to consider.

Thanks for that last page, the patched version of MPD sounds amazing!

Sounds great and it's a nice case too! It also stays pretty cool: 47 C at 25 C ambient temperature. See the setup below and the connection to the V-Link in the second picture. The direct USB connector is mentioned here on the forum as well. I really like the sound of it when it's combined with the linear PSU.

Hi Richard, the Beaglebone you mention would compare well to my earlier setup. I used a stock router (TP-Link TL-WR1043ND) and put OpenWRT on it. With some effort I managed to get MPD working. The sound from these small systems is really clean, almost as if you can hear the fact that there are less components installed on the mainboard. The only drawback I could find to this system was that playback of larger, better quality audio files was not 100% stutter-free. Maybe the Beaglebone will do fine, as its CPU is a bit faster. About the location of the audio files, I think I might compare both options. 64 GB won't be enough to store my entire collection, but I should be able to make a selection. NFS or Samba will both do fine in a streaming configuration. I think there's a comparison of both floating around the internet. The mmap option refers to memory mapped I/O, as you already said. Instead of copying data around, only pointers to buffers are exchanged, which I think might contribute to less jitter. When I turned on this option, the soundstage got a bit cleaner. *:24_3:2 tells ALSA to leave the samplerate unchanged, and output the data in the S24_3LE format across two channels. This is the format the V-Link understands. Data is sent bit-perfect without any form of processing. The PREEMPT RT kernel is available in the Debian repository (linux-image-rt), at least in the 686 and amd64 flavors. For ARM you still have to download, patch and compile the kernel yourself. I am also unsure if support for high-resolution timers has been added for ARM yet.

Hi all, I've been a long time reader of the CA forum and in this first post I want to ask your opinion on my fanless build. It will be a headless server, based on MPD and RT Linux. I'll stay with the CAPS design philosophy as closely as possible. I just ordered the parts and will keep you posted on my progress. This is my setup: Akasa Euler fanless case Gigabyte GA-H61TN (thin mITX mainboard) Intel Pentium G630T OCZ Vertex 64 GB SSD For a review of the case, see: Akasa Euler Fanless Thin ITX Case | silentpcreview.com Other components: Musical Fidelity V-Link (on its own linear PSU, circumventing the USB power line) Metrum Octave + linear PSU Duson PA-100 (Class A stereo amplifier) All my music will be placed on either the SSD or on the network and MPD can be controlled through my phone or tablet using one of the available clients. Once it's up and running, it's really convenient. As for the software I'll be using MPD on (stripped-down) Debian Linux, because of my experiences with this combination. On an earlier build I really came to love the sound of the PREEMPT RT kernel. Despite the disbelief I noticed in other threads by some of the audio qualities of a real-time Linux kernel, I really want to say that it did wonders to my previous setup. Voices are so clear, they almost seem visible in space like a hologram. Audiences and drum sounds in live recordings sound very realistic too. To make full use of the real-time kernel, you need to prioritize the threaded IRQs, which can be done effectively by using the rtirq scripts by Rui Nuno Capela. Then there are some small adjustments, such as increasing the priority of the MPD process and setting the processor affinity for each process, working towards placing MPD on its own CPU core. See this guide for some useful tips (based on Voyage MPD): ????? Furthermore, I'm using the following ALSA configuration in my MPD.conf, allowing me to make use of the async-USB properties of my USB-S/PDIF converter: device "hw:1,0" format "*:24_3:2" use_mmap "yes" auto_resample "no" I suspect some people on this forum are using similar configurations and I'm interested to hear how they compare their own setups to the more expensive servers and appliances of the established brands. In short, has anybody used the Akasa Euler case for a CAPS before? And does anyone have good tips on how to get the most out of my setup? I'd really like to hear your comments and tips! Regards, Vincent