Hello, I have just gotten my account here going, thanks for your help. I have been looking around and can see no discussion regarding USB output. I have a Soekris dac1321 that I would like to try with SMPD, and looking to see if that is possible
Thank you,
Skip Pack
Hellow Skip Pack,
Welcome to the SMPD R&D Club.
I'm also using the Holo Spring2 DAC with the r2r system. So I'm very interested in the Soekris DAC.
Information on SMPD's i2s driver support could be found here. Please let me know the result of running it.
Thanks.
Thank you for the reference to the compatable dac/driver list. I think it answers my question. The Soekris dac1321 is a finished dac and does not have an I2S input. I have been using it with my Rpi4 and Moode. the dac1321 has both USB input and SPDIF.
Looking at what I see reflected of SMPD history, the new 1.0xx versions have not been developed (yet) to take advantage of the much improved USB capabilities, either for directly connected music libraries on external USB drives or for a dac with USB input. With the prior RPi versions I fully understand why the input is restricted to NAS, and the output to I2S connections.
I do have a Allo digione card that I can use with an RPi 3B+, to connect to the dac1321. That will take a modest bit of reconfiguration, but it should be fine, and give me a good path to experience SMPD.
Thanks again, Skip
Unfortunately, symphonic-mpd does not support USB DACs.
I used to use the Amanero Combo 384 and S/PDIF.
I always thought that was the sound of my DAC, but one day when I started to think about replacing it, it occurred to me to remove the Combo384 and later use the I2S input directly from the Raspberry Pi2 to the remaining exposed I2S jacks.
At the time, I was using them in my DAC slave.
In other words, the clock source was a Raspberry Pi2 PLL. Even under these adverse conditions, RPi's I2S gave me a glimpse of the true performance of my DAC.
Those DDCs and receivers on my DAC did not seem to have any consideration for sound quality.
There are many choices of transports that support USB, whether Windows, Mac or Linux.
On the other hand, transports that can output I2S have been very limited, including products that run asynchronously, such as DDC and FIFO, and single board computers.
The lack of a transport that would fit my needs, and the fact that the I2S output of a single board computer can vary greatly in sound depending on software and settings, led me to build a crafted Linux called symphonic-mpd.
As for the output to the USB DAC, I haven't been able to test it here.
At the very least, you should have to set up your playback software to use the ALSA drivers.
Maybe you are missing a kernel module needed for the USB output. In that case, you'll need to change the kernel configuration and rebuild it.
There may be a problem with the compatibility of the Xenomai kernel and the USB driver.
You may also need to review the thread affinity and priority settings in /etc/rc.local.
As for the source of the kernel and driver, we are manually tuning hundreds of points by acquiring the profile data in the I2S output to improve performance.
These tweaks not only provide no benefit to the USB output, but in some cases may cause a performance degradation.
The symphonic-mpd specializes in I2S output and is not good at anything else.
Hi Skip,
Oh, I see the Soekris dac1321 wasn't a board. It's unfortunate you can't connect it directly with i2s.
Papalius' faith in the i2s is considerable, so I think expecting him to develop a system for USB connectivity is like expecting a miracle.
If you insist on a USB connection, I recommend you to use "lightmpd". You can find information about this software on this page of my site. The description on the linked page is about Intel hardware, but there is also a version for Raspberry PI. It's in Japanese, but Google Translate will help you make sense of it.
Of course, SMPD is also a great music player, so I wish you love it.
Regards
