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PKeith
3
Feb 9, 2018
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Does anyone know if you can connect to the DX7s DAC via usb on a Linux based host (like from Volumio)? Thanks..
Feb 9, 2018
JCruk
101
Feb 9, 2018
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Based on the updated XMOS chip and comments below, it looks like it'll work with recent linux kernels. I sure hope it does!
Feb 9, 2018
slugman
67
Feb 9, 2018
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per JCruk's reply, it uses the XMOS chip. I've had no problems using Slackware 14.2 x86_64 in recognizing my Sabaj Da2 (XMOS), or my Topping NX4DSD (also utilizes XMOS).
The biggest thing you need to worry about is if you are using ALSA or PulseAudio. You want to use ALSA, because ALSA will play the stream directly on the hardware. Unfortunately Pulseaudio literally remixes everything into 48Khz--regardless of the sample rate of the input file. I confirmed this by playing a 32/384 file and realized that pulseaudio downgraded it to 32/48. I was soooo pissed.
Most modern distributions use pulseaudio. It is possible to downgrade to ALSA, but the procedure is different for every distro.
You can easily check if your dac is downmixing, first grab a 32/384 file from the following testbench site: http://www.2l.no/hires/index.html
Figure out which card your dac is: aplay -l
Then run the following command (make sure you use the correct card# from the command above): cat /proc/asound/card0/pcm0p/sub0/hw_params
Feb 9, 2018
earlgrey77
27
Feb 17, 2018
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"Pulseaudio literally remixes everything into 48Khz" This is not quite correct. But it is the default behavior. I am on Ubuntu 16.04, and I have configured Pulseaudio to output 176.4/192 KHz to my XMOS device. For playback of 48k files, it would choose 192k, and for 44.1 files (or streams) it would output at 176.4. You can also tell it to use a better upsampling algorithm.
Feb 17, 2018
slugman
67
Feb 17, 2018
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That is true, however i would rather have alsa stream it directly to the hardware though. Although, i should probably adjust the default sampling rate. Reverting to alsa is a pain in the ass and i honestly dont have it working quite correcly. I had to remove the pulse audio libraries and recompile deadbeef, so at least thats able to use alsa with my dac . I was able to turn on pulseaudio for a seperate sound card though for the rest of my applications. For this reason i mostly use my dac with my android phone, and im saving up for a decent dap.
Feb 17, 2018
earlgrey77
27
Feb 18, 2018
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Interestingly, I have found to achieve better results (i.e. improved treble resolution, cleaner sound and reduced stress / fatigue) with upsampling at the source. For a long time I had favored bit perfect playback, but with the rise of 352k+ devices like XMOS I found that this is no longer desirable. On Android I use UAPP with the setting "Resample to highest sampling rate of the DAC", which produces 352k. And on Ubuntu we are limited to 192k, since Pulseaudio does not support 352k or higher rates. Both setups are satisfying to me, particularly for less-than-perfectly produced files and streams, which I find less bearable with bit-perfect playback at 44.1/48k. I believe that this is the reason why so many people prefer upsampling and / or DSD conversion at the source and before the audio leaves the player (even if the audio material has not been produced that way).
Feb 18, 2018
slugman
67
Feb 18, 2018
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alright so I just made the changes. I set my primary sample rate to 176.4k and the alternative to 192k. I have to say I'm actually impressed. I was skeptical because I played with upsampling plugin in deadbeef . I honestly wasn't very fond of it because it would generate artifacts randomly (pops and clicks). I was skeptical that my experience would be the same in pulse audio. I would prefer to have my dac perform the upsampling (bit-perfect playback)--my dac is already upsampling to 32 bit audio (ess9038). So far, its been a positive listening experience.
Feb 18, 2018
earlgrey77
27
Feb 19, 2018
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Let's document this, other readers might be interested as well:
cat /etc/pulse/daemon.conf ...
; resample-method = speex-float-10 resample-method = src-sinc-best-quality
default-sample-rate = 176400 alternate-sample-rate = 192000
...
And to restart: pulseaudio -k
Feb 19, 2018
slugman
67
Feb 19, 2018
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Good idea. Also, good call on the resample method, I will add that now.
Feb 19, 2018
scoopbb
155
Mar 26, 2018
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thanks, this was very useful. why set the defalt to 176.4 out of curiousity.
does either default or alternate hold priority if the files are actually that sample rate and the other is just fallback if they dont?
Mar 26, 2018
slugman
67
Mar 26, 2018
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From my understanding, the default holds priority. The alternate is used when you have things that are not 44.1 multiples (i.e. dvd audio at 192 or other hi res stuff).
I set the default to 176.4 because thats 44.1 * 4 (so 4 times upsampling). Really it depends on what your dac can handle, but the value you settle on is personal choice really. My ess9038 pro (same dac thats in DX7s), can handle up to 512 pcm, so I could bump it up more. I'll mess around with it when I get home and let you know.
The unfortunate thing is, this is all pulse audio resampling. I chose 192 as the alternate because thats the highest sample rate flac files that I have. (Although, I suppose those 192 files can easily be upsamples to 384.)
Mar 26, 2018
slugman
67
Mar 26, 2018
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actually pulse audio may max out at 192. Let me do some more research later and I'll report back (may be a day or 2).
Mar 26, 2018
scoopbb
155
Mar 27, 2018
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thanks, appreciate it
Mar 27, 2018
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