WiiM Ultra optical output with volume control

[pieterv1]

I've done some searching and might have seen this question answered in the past, but just a quick double-check:

How is variable volume control handled by the WiiM Ultra (and probably WiiM Pro/Mini as well), when using the optical output?

Is it a 24 bit output to utilise the max resolution possible over a toslink/coax connection? This to reduce any possible degradation/maintain dynamic range at lower volumes (I know it'll be hardly noticeable)

 

[hgo58]

I've done some searching and might have seen this question answered in the past, but just a quick double-check:

How is variable volume control handled by the WiiM Ultra (and probably WiiM Pro/Mini as well), when using the optical output?

Is it a 24 bit output to utilise the max resolution possible over a toslink/coax connection? This to reduce any possible degradation/maintain dynamic range at lower volumes (I know it'll be hardly noticeable)

Volume control and other DSP is done with 32 bit. This is output on digital outputs depending on the configured values.

 

[pieterv1]

Volume control and other DSP is done with 32 bit. This is output on digital outputs depending on the configured values.

View attachment 34745

Ah I see there's the "fixed resolution" toggle so I could technically force it to always stick to 24-bit?

And sample rate will still be adaptive?

 

[hgo58]

And sample rate will still be adaptive?

No, fix resolution is fixed sample rate and fixed bit rate. Unless you need it to be fixed, leave it variable.

 

[pieterv1]

Hm so playing a file at 16bit will automatically set the WiiM's optical output to 16bit? Even though you might be listening at lower volume?

Seems like we might benefit from a separate toggle to fix the bit depth OR the sample rate? Or am I overseeing something?

 

[Aquaman]

Hm so playing a file at 16bit will automatically set the WiiM's optical output to 16bit? Even though you might be listening at lower volume?

Seems like we might benefit from a separate toggle to fix the bit depth OR the sample rate? Or am I overseeing something?

If my understanding is correct the Ultra will upsample everything to 32 bits. For volume control it will cut off empty bits from the top and then downsample again to the desired/original bit depth. I‘m sure I have over-simplified things here or may even have gotten it wrong. In any case, don‘t worry about it. All is good.

 

[pieterv1]

If my understanding is correct the Ultra will upsample everything to 32 bits. For volume control it will cut off empty bits from the top and then downsample again to the desired/original bit depth. I‘m sure I have over-simplified things here or may even have gotten it wrong. In any case, don‘t worry about it. All is good.

Yes I understand that up to a certain point in the DSP, everything is processed in 32 bit

But following the logic behind doing so, you'd expect it to "max out" the digital outputs as well - always outputting at 24 bit, but this does not seem to be the case?

I'm asking because I might finally take the plunge and buy the Vibelink, where the recommended connection method seems to be over optical/coax + I just enjoy getting down to the nitty-gritty of all this

 

[Aquaman]

Yes I understand that up to a certain point in the DSP, everything is processed in 32 bit

But following the logic behind doing so, you'd expect it to "max out" the digital outputs as well - always outputting at 24 bit, but this does not seem to be the case?

I'm asking because I might finally take the plunge and buy the Vibelink, where the recommended connection method seems to be over optical/coax + I just enjoy getting down to the nitty-gritty of all this

I appreciate your inquisitive approach. I hope we get an answer here from someone who really knows.
I‘m kind of in the same situation, feeding a Mini into a pair of active wireless speakers via optical.
My setting is max. 48 kHz (I don‘t own anything higher than that) and 24 bits. But left it at variable. I‘m pretty sure that this the optimal setting for me. But why?