Another USB hub question

While we're at it.
Why are the connectors used in audio still USB A? I would have thought that USB C is the new standard.
Probably because it's not. 😛 At least not yet. USB A is not officially deprecated in any way.

It makes sense to use the form factor that is most commonly used, which is a moving target of course. Mechanically, USB A might not be great, but from my point of view it's better than USB C for a permanent connection.
 
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... While coming from Fiio themselves. Quote (re. the Fiio Warmer DAC):
Notes:
1.Typically, set UAC to UAC2.0. If connecting to devices like PS5 or Switch, switch the UAC mode to 1.0.
2.OS/NOS settings are only effective in USB decoding mode.
It doesn't say which setting is used for optical and coax though just that you can't switch.
 
Quoting John Darko: TOSLINK and coaxial inputs operate only in NOS mode. If you insist on OS mode, you’ll need to feed the Warmer over USB. FiiO hasn’t confirmed this explicitly, but we might reasonably assume that the OS mode’s mathematical processing must run on the Warmer’s USB receiver chip, through which S/PDIF signals do not pass.
Well. Darko or not Darko I believe more on my experience rather than in his words.
Regarding you…You can believe who you want.
I only told my real experience
 
Well. After changing the switch, which is a manual switch in the Warmer, the sound I get is very different.
In that case either Fiio are lying about the switch only having an effect in USB mode or this is the ultimate placebo effect 🙂
 
In that case either Fiio are lying about the switch only having an effect in USB mode or this is the ultimate placebo effect 🙂
Immagine 2026-02-08 113645.png
From Fiio User Manual
AM(Oversampling settings):The default option is OS and over sampling is on. When external audio datas transform to the K11 R2R, it will be oversampled and converted to a 384k sampling rate (in simple word: upscaling). Then the data will be sent to the R2R module for decoding. The purpose of oversampling is to change the distribution of quantization noise and improve the SNR.

The sampling rate displayed on the K11 R2R is still the original sampling rate but not 384k.

When the SAM option is set to NOS, oversampling is off. The audio data will be decoded and processed in its original sampling to present the original sound experience.
It doesn't say it's only available via USB

The thing is different for Warmer :

Based on recent reviews, the FiiO WARMER R2R DAC/Tube Buffer has specific limitations regarding NOS (Non-Oversampling) and OS (Oversampling) modes when using the Coaxial input.
  • Coaxial/Optical Input Limitation: The optical and coaxial inputs on the FiiO WARMER R2R operate only in NOS mode.
  • USB Requirement for Switching: If you want to use the OS (Oversampling) mode, you must connect the device via USB.
  • Reasoning: The oversampling mathematical processing, which drives the OS mode, likely runs on the USB receiver chip rather than the S/PDIF (Coaxial/Optical) path.
While the physical switch on the back allows toggling, it will not change the sound signature from NOS to OS when using a coaxial source.
  • Coaxial Input: Functions in NOS mode (more fluid/relaxed sound).
  • USB Input: Supports switching between NOS and OS modes (OS offers a sharper, faster vibe).
On my side I have :
K11r2r > Coaxial
Warmer > USB
That's all
 
Thanks, that's surprising. Seems like in Fiio's PR department the right hand doesn't know what the left hand does, which led to my (false) information. Good to know it works, and thank you Maurizio!
 
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From Fiio User Manual
AM(Oversampling settings):The default option is OS and over sampling is on. When external audio datas transform to the K11 R2R, it will be oversampled and converted to a 384k sampling rate (in simple word: upscaling). Then the data will be sent to the R2R module for decoding. The purpose of oversampling is to change the distribution of quantization noise and improve the SNR.

The sampling rate displayed on the K11 R2R is still the original sampling rate but not 384k.

When the SAM option is set to NOS, oversampling is off. The audio data will be decoded and processed in its original sampling to present the original sound experience.
It doesn't say it's only available via USB

The thing is different for Warmer :

Based on recent reviews, the FiiO WARMER R2R DAC/Tube Buffer has specific limitations regarding NOS (Non-Oversampling) and OS (Oversampling) modes when using the Coaxial input.
  • Coaxial/Optical Input Limitation: The optical and coaxial inputs on the FiiO WARMER R2R operate only in NOS mode.
  • USB Requirement for Switching: If you want to use the OS (Oversampling) mode, you must connect the device via USB.
  • Reasoning: The oversampling mathematical processing, which drives the OS mode, likely runs on the USB receiver chip rather than the S/PDIF (Coaxial/Optical) path.
While the physical switch on the back allows toggling, it will not change the sound signature from NOS to OS when using a coaxial source.
  • Coaxial Input: Functions in NOS mode (more fluid/relaxed sound).
  • USB Input: Supports switching between NOS and OS modes (OS offers a sharper, faster vibe).
On my side I have :
K11r2r > Coaxial
Warmer > USB
That's all
So which input are you using on the Warmer? Maybe the K11R2R does support NOS/OS with coax input but that is a different device.
 
So which input are you using on the Warmer? Maybe the K11R2R does support NOS/OS with coax input but that is a different device.
USB on the Warmer. Anyway in both devices i mainly use NOS. From time to time I switch to OS
 
The OS/NOS switch does work on USB so I am not sure why you thought Darko was wrong when he said the switch didn't work for coax or optical.
I was referring to the K11r2r. The references I found say that the K11r2r Nos/Os also works in Coax
 
Not to contradict you, but the first post, which was by Wee Bee, referred to K11r2r. My comment was in response to his post.
 
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