Lag starting Each Track - Using Optical Input

[Ziggy]

I have my WiiM Pro being fed through its Optical Input*. I have the Optical Output set to fixed resolution 24/96.

For each track, there is a millisecond or first note delay. This happens on every track.

I don’t get this delay using Tidal Connect nor AirPlay.

* The long story is that I am streaming Lossless H-Res Apple Music through an old iPhone using the CCK, That goes to USBC to Optical converter (SMSL PO100 2024) into the WiiM Pro.

Any ideas on this? Is it expected through the Wiim’s optical input?

 

[Burnside]

Have you any other means of testing the optical input? Might there not be latency involved in the conversion chain?

 

[rubato]

I wouldn't expect WiiM to be able to do very much about gaps in optical or audio input. With wifi or ethernet, the device can pull data ahead of when it's needed, so it can request the next track while the current track is still playing. Can't do that, as far as I know, with SPDIF.

 

[Ziggy]

I assume the WiiM is taking a second to lock on to the signal from the PO100.

I’m going to try to go from a WiiM Mini via Toslink to the WiiM Pro just to add to the troubleshooting info.

It seems like some people are happy with the PO100, so I am guessing there may be a setting somewhere. I tried swapping Toslink cables and it was no help.

 

[Ziggy]

I set it up to go from a WiiM Mini via Toslink to the WiiM Pro. I expected it to not have the 1 second silence but it did.

When I set the mini to have max output of 24/192, there was the silence. When I set the mini to have max output of 16/44.1, there was no 1 second silence.

So it seems to me that either the Mini and the PO100 have the same error, or the WiiM Pro has a problem with the optical input.

(Uptodate firmware on both units, streaming using Tidal connect.)

 

[Ziggy]

Can anyone who is streaming Apple Music from an iPhone cabled through a DDC to the WiiM Pro optical input confirm whether there is 1 or 2 seconds of a track ignored/silent when the bitrate changes?

I have tried the SMSL PO100 and the Douk Pro. Each of them have the silence. WiiM support has escalated the problem but I am losing hope that this solution works. I wonder if there is different WiiM Pro hardware versions, some work, some don’t.

-Ziggy

 

[jazd]

I am experiencing something very similar with USB audio output from a PC via a SMSL PO100 to the optical TOSLINK port on a WiiM Amp. I've noticed that when nothing is playing it takes about a second or so to recognise the signal and start outputting audio. Until I saw this thread I assumed it was the PO100 or the Windows driver.

 

[Ziggy]

I am experiencing something very similar with USB audio output from a PC via a SMSL PO100 to the optical TOSLINK port on a WiiM Amp. I've noticed that when nothing is playing it takes about a second or so to recognise the signal and start outputting audio. Until I saw this thread I assumed it was the PO100 or the Windows driver.

Yes, this sounds like it may be the same issue. Do you actually not hear the first few notes or are they just delayed?

I am confused that others don’t report this problem.

Here is what WiiM Support said:

“It’s not a hardware issue — this is a limitation: switching sample rates requires time to re-lock the signal."

 

[jazd]

Do you actually not hear the first few notes or are they just delayed?

I do not hear the start of the sound, it is very noticeable when a notification sound is played. It will cut off the start of the sound.
As far as I can tell, the SMSL PO100 is continuously outputting a signal, as indicated by the driver setting, and the LED light on the hardware itself.

“It’s not a hardware issue — this is a limitation: switching sample rates requires time to re-lock the signal."

Are you actually switching sample rate though? I am not, the SMSL should be outputting a continuous 48Khz audio stream. It seems like the WiiM is detecting that the stream is silent and going into a low power mode, which then takes a bit of time to come out of and "re-lock the signal".

 

[jazd]

I just did some testing here and it seems that if I play any sounds within a 2 minute window it works flawlessly and instantly. If I don't play any sounds for 2 minutes, then I will experience the delay and the sound will be cut off.

Edit 1 - changing the WiiM standby mode from 2 minutes to 1 hour made no difference
Edit 2 - I get the exact same behavior when connecting the SMSL to an Android phone, same 2 minute timeout after which the audio is cut-off. So that rules out the Windows driver as the culprit.
Edit 3 - Playing a silent track does not prevent the issue, the stream still goes into "standby mode" after 2 minutes.

It seems like your situation is a little different in that it happens between every track you are playing, where the bitrate and/or sample rate is changing?

 

[Ziggy]

It is when I am playing from my iPhone -> SMSL PO100 -> SMSL AO300 amp.

It happens whenever the bitdepth/sample rate of the Apple Music changes. So if I am shuffling, it happens quite often. If I play an album through, it doesn’t happen between songs.