Hello everyone, I read in the Uniti Nova specs that the maximum audio resolution at the Toslink optical input is 24 bit and 96 kHz, yet if I try to play an audio ALAC track at 24/192, for example, the display reads 192kHz… how is this possible? I would have expected to see 96kHz (from downsampling), or not get any listening at all. Has Naim made some HW or SW updates to the Uniti Nova?
Info here;
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The Toslink audio ports, as a standard, are only certified up to about 3Mbps. So the reality is that 24/96 is all you are guaranteed but that’s with the faster non Audio Toslink. Vendors are free to manufacture optical transducers that conform to the Toslink Audio standard and exceed it. You’ll get higher 15Mbps out of the non audio Toslink.
If a device sticks to Toslink Audio and does not exceed the standard, you’ll only get 16/48Khz PCM.
I have a few devices that are limited to that.
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I agree with you, but then why when I play a 24/192 ALAC file both the Uniti display and its configuration web page show 192 kHz (please see below picture)? Shouldn’t I be reading 96? I should also be reading the depth as 24, not 16 as I actually see, as well as the bitrate which I would expect to be limited to 3000 kbps, instead of a “miserable” 1536. I use a Raspberry pi 4 with Raspberry pi OS lite, with the HiFiBerry Digi2 Pro HAT which supports toslink up to 24/192. The player is Plexamp headless, in its latest released version.
Thinking it could also be a software limitation, I also tried Roopie and HiFiBerry 64 OS, but without noticing any benefits.
If you try playing 24/192 over Toslink it will either play at 24/192 or it won’t. Nothing would get downsampled on the fly to cope with a cable that couldn’t handle it, so I suspect you are right, the software in your RPi may be doing it.
I checked all the configuration options available in both the raspberry and Plexamp, everything appears to be set correctly. The optical cable could limit something, although I would not see it realistic: an optical cable does not influence the transfer of digital information in this way. Or could it be the Naim configuration web page that reports incorrect measurements at the digital inputs (RCA, Toslink)?
Today update: continuing the search for the cause, also trying Roon and HiFiBerry OS 32bit, without any news, now playing a 128kbps mp3 file… what a surprise, the playback indication on the Naim web page was displayed as 16/44 1536kbps (yes, I have already refreshed the page), instead of 16/44 128kbps as expected. So could the anomaly be in the Naim web page? I am confused, quite a bit.
I check the active parameters of the audio device, the output is shown in the screenshot below. This is proof that I am getting bit-perfect playback! So the problem seems to be limited to the web configuration page of my Uniti Nova! What does it report to you? Otherwise should I be afraid of my Uniti’s digital inputs faulty?
Oh you’re playing back via Plex? I’d check the logs. Plex is terrible for transcoding even when transcoding is explicitly turned off.
Also bear in mind, that output shows the card is capable of on the stream but the SPDIF out can be different.
I have a sound card that renders 24/192 but as soon as a stream is redirected to optical output, it drops on-the-fly to 16/48.
Thank you for your answer, I just received from HiFiBerry’s support team that the command I used to check the Toslink audio output quality is correct: it really indicates the quality output through toslink on what effectively I’m playing in that moment. I also checked Plex log looking to every transcoding action, no traces (in fact this is exactly what I found by the raspberry-HiFiBerry unit, as also reported on the above screenshot). Could you kindly tell me about your experience with the Naim configuration web page, I mean whether you correctly view the quality of the audio files playing from the digital inputs?
I’ve only ever used the Uniti Qute2 and NDX, but I’ve also never had an issue with mismatched data display. I’ve had both for well over a decade and what was seen on the screen (prior to the screens dying) always matched what I saw in the Naim app. Those older Naim streamers don’t have the built-in web page like on your Nova.
I do have some newer Qb2 on the same streaming platform at the Nova. And a transport that supports hi-res output over Toslink. But I don’t really feel like carrying one down three flights of stairs to test. Currently, I only use the Qbs over wired ethernet streaming.
Which I suppose brings up a tangential question: the Nova is very capable. What are you using the HiFiBerry for that the Nova cannot already do natively?
You see, on the Uniti screen I read 192kHz when I play a 24/192 ALAC file, which is very strange because it comes from the toslink digital optical input (shouldn’t it be limited to 24/96?)! I use the Raspberry with the HiFiBerry digi2 pro card, which with Plexamp headless acts as a bit-perfect optical streamer on the Naim. I would love the Naim’s native Ethernet streamer, but lacking the ability to create smart playlists I had to give up (Plex is way ahead in these aspects).
I think you misunderstood my first post.
24/96 is all that’s “guaranteed”. If both the sending and receiving side adhere to but do not exceed the Toslink non audio standard. But many implementations exceed the standard.
However, the manufacturer only knows the capabilities of their side of the connection so all they can really publish is support for 24/96 even if they think their can do higher.
In the case of SPDIF, it is not a negotiated protocol. it’s one way. So if your soundcard says it is outputting 192, and the Nova is displaying 192, then that is what is happening. If it could not accept the stream, it would not automatically shift down to 96. You’d simply get no sound.
Yes it is, for this reason now I’m soldering a bnc connector to the digi2 pro pcb to be more “sure” for 24/192 playback (through coaxial SPDIF cable), even if still remain my dubt about the nova’s configuration web page (just updated to 3.11 firmware, no way).