There is an anomaly of file handling between the Lumin U1 Mini and my DAC

I am a fan of Roon and I like Lumin. But Lumin U1 Mini is the only transporter I used. Maybe competition is better. I find that there is a technical problem that bothers me. It is not about SQ, it is only technical. And I feel that I want to share this.

Please see this thread in Audioshark forum

My message is that be careful. Lumin U1 Mini does not transport 32b flow to all DACs as one can believe reading their internet page here :

And here is my problem:
Lumin shows 32b, custom upsampling set to 24b, Lumin display still shows 32b, my DAC shows 24b
Lumin shows 32b, custom upsampling off or set to native, Lumin display still shows 32b, my DAC shows 24b
My conclusion is that the Lumin U1 Mini is not capable to transport 32b to my 32b DAC
I understand Peter showed us a proof of a DAC capable of reading the 32b from Lumin
But it is a big problem that these 32b are not transported to every 32b capable DAC
This is not a SQ thing, this is only something related to honesty and support

Proof that Lumin USB outputs 32 bit from Roon using RME ADI-2 Pro FS DAC native bit test:

Lumin USB 32-bit output was tested OK with some DAC based on XMOS USB chip and ITF USB chip. In case of the DAC using ITF USB chip, a corporate customer tested it for us.

DAC-specific issue cannot be investigated without a DAC being accessible by us. Besides, if 24-bit works, then it’s not a great problem as 32-bit is not offering any gains at the DAC. (32-bit is only useful as an intermediate step in signal processing.) According to Stereophile measurements, no existing DAC has higher than measured 22 bit resolution.


And by the way as it is stated in the Audioshark forum, my DAC shows entry of 32b when the Roon stream is sent by my PC. It shows 24b when the signal is handled by Lumin.

My conclusion is that on my setup, the problem comes from the Lumin. And if I have this problem on my setup, it may happens with other setups

Hi Peter
any idea about why my 2k Lumin U1 Mini is not sending 32bits stream to my Sony TA-H1ES DAC via USB while my 400$ HP connectected with the Sony ASIO driver does send 32 bits flow?

I know you cannot test what you say on the Lumin U1 Mini page with all the DACs but I am sure that 99% of the people who go here (on Lumin U1 Mini webpage)

and see these specs would think that Lumin U1 Mini is supposed to send 32 bits flows to all 32 bits capable DACs.

The fact is my DAC is a 32 bits capable DAC but Lumin U1 Mini is not configured to correctly send the 32 expected bits. Please see video above

Anyway Peter I bought a Lumin U1 Mini thinking it is a 32bits player but it does not delliver what is expected with my 32 bits DAC. So I want this resolved. It is not acceptable

I dont really care and nobody should care with some test you did with some unknown DAC
I want Lumin U1 Mini to send 32 bits flow to my Sony TA-H1ES 32 bits DAC
It is stated in your webpage that it is a 32 bits player
So why it is not working with my 32 bits DAC? This is outrageous
That means that what you state in your Lumin products specs may not work with all the related setups
This is a big thing one should have in mind!

I understand your frustration that it‘s not working as expected. I’m sorry for that. I know the feeling.

All my experience with digital Hi-Fi systems (which are just specialised computers, so it’s about integration and implementation of hardware, software, protocols, firmware) tell me that no supplier can forsee all possible configurations. So the bitter truth is: these things happen when you combine components.

Maybe it helps getting over your anger that you could assume that LUMIN did not try to trick you into something (at least I can not imagine that)?

For now you learned something: that there’s an issue with that specific setup. Maybe you are the first one who discovered it?

Anyhow, you have to decide what to do. Will you await an answer from LUMIN if this can be fixed? Will you return the LUMIN? Will you get another DAC that will receive 32bit from the U1Mini (Peter can for sure recommend one). Or will you be OK with “just” 24bit? Or maybe you upsample everything to DSD (I do not know if your DAC supports that).

What will you do?


Is the Sony DAC not resampling all PCM input into DSD?
So the best solution will be (U1 mini is only supporting DSD 256): Let the Roon DSP resample to DSD 256 and compare it with the native or to 32 bit resamplet music.

Thanks for your time
I don’t know what to say. I don’t really know what to think about what you say… But clearly I will not go your way

This is the first time of my life I buy a high end product of which specs are not what they really are

Maybe you have very big experience about stuff and equipment and your experience says that this ■■■■ happens

On my side, on the future, I will stick and I will encourage people to stick with products one can trust

And I will continue to do some Lumin bashing until my problem is solved

The RME DAC Peter illustrated is hardly unknown and is highly regarded.


The test proves that Lumin is able to output 32-bit. We also output 32-bit to XMOS and ITF-based USB DAC (recent Esoteric). Every DAC is different, especially for Linux. Take native DSD for example, many DAC is able to do native DSD in Windows but not in Linux.

  • If your DAC shows the same problem with another Linux Roon Bridge, then your DAC has a limitation in Linux.
  • If your DAC shows 32-bit with another Linux Roon Bridge, then the current Lumin firmware has a limitation with your particular DAC.

Again, 32-bit data is not significant at the DAC end unless you’re doing further digital processing that is built into the DAC instead of before it (in the Roon Core).


I was going to say what Peter just said.

Their is no Linux driver for the Sony DAC so any Linux based device or computer will fall back to standard USB 2 class audio driver and may miss out any DAC specific features such as 32bit support or native DSD. If hardware manufacturers don’t release one it can’t get into the inner workings of Lumin and other devices. A lot of DACs have just drivers that run on Windows and don’t look to support other OS.

Lumin use Linux as the backend of their internal software the same as many hardware vendors do, they often try and add support for DACs not supported normally under Linux but need to have the DAC and the resources to hand and it needs to be worth the investment. This same issues can also affect Roon’s Nucleus if DAC is directly attached.

I would reach out to Sony and ask them what Linux support they have and what might or may not function. This is not just a Lumin issue and blaming them solely is highly inappropriate. Saying this perhaps Lumin’s marketing needs to be more clear on the fact it’s Linux based and support is dependent on the DACs support for this.


Hmm ok I see
So specs depend on the OS used in streamers and DACs. And are only true for particular cases. Well I just learned something

But ASIO driver is not a Linux driver? It is not a driver that can work in both platforms? Sorry for my limitations here

FYI my PC sends 32bits using ASIO driver and my DAC reads the 32bits. Is this something useful to know?

ASIO is for Windows only and its use provides the interface between windows and the audio hardware, which is why it works to give full function to the DAC.
Without the ASIO driver you would be working like you see in Linux in that the you would get a common, reduced set of capabilities that apply to all DACs.

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From Sony’s website - explicits missing is Linux or anything non Windows or Mac

System requirements

Hi-Res Audio Player can be used in the following system environment.


  • Windows 10 (32 bit/64 bit)
  • Windows 8.1 (32 bit/64 bit)
  • Windows 8 (32 bit/64 bit)
  • Windows 7 (SP1, 32 bit/64 bit)
  • Windows Vista (SP2, 32 bit/64 bit)
  • Mac OS X v10.6, 10.7, 10.8, 10.9, 10.10, 10.11, 10.12


  • One of the above operating systems should be installed by default. Upgraded operating systems and multi-boot environments are not supported.
  • We do not guarantee operation for all computers even if they meet the above system requirements. Furthermore, the following systems are not supported:
    • Personally constructed computers or operating systems
    • Upgraded operating systems
    • Multi-boot environments
    • Multi-monitor environments

Thanks but these specs are for HiRes audio player which is a generic player developed by Sony. Did you see these specs related particularly to my Sony DAC?

Yes understood thank you
Many things one should learn before buying

No mention of Linux which normally means you get what you are seeing, generic device support only or it doesn’t work at all.

based on the Sony TA-H1ES DAC I didnt manage to get an exact match, but this is typical of such companies not to support Linux based systems. maybe you meant this Sony TA-ZH1ES DAC

“Roon Rock runs on Linux. Native DSD only works with Linux if a driver is written for the specific DAC being used. Thus far, there is no Linux native DSD driver for the TA. But who cares, it makes literally no difference to what data is converted to analogue inside the TA. Chill out!”


When I upsample flow to DSD in Roon, Lumin correctly outputs DSD signal to the TA which recognizes it. Isn’t this weird that DSD playback is correctly ouput but not 32 bits?

Anyways I discover I have many similarities with Jon Snow. I know nothing
The only thing that I know is that I am angry to have bought a Lumin while I could just use my laptop with a high end USB cable…