How can I tell my U2 Mini is outputting 32bit to dac?

I’ve been assuming that my U2 Mini will send 32 bit files to the dac without changing to 24bit. I have resampling turned off and all other volume control or processing is off as well.

I am playing 32 bit DXD files with Roon. Roon says its passing the file as 32bit, and the Lumin interface also shows 32 bits (see screenshots). I am using USB output to the Holo May which shows the 384K on screen but does not show bits.

The distributor for my Holo May dac told me today that the May is a 24bit only dac and that it can’t be playing these files.

Is the Lumin downsampling the file to 24bit? Is there a way to see what the Lumin’s output is to the DAC?

I have had both 24bit and 32bit versions of the same DXD files from record companies, and doing comparisons, I hear a definite improvement with the 32bit files, they sound more like DSD than PCM, warmer, smoother, more laidback with a more subtle details.

32 bit

Some USB DAC accepts 24 bit but not 32 bit. In this case, Lumin sends 24 bit to the DAC. This is automatic, is done only when necessary.

When connected to a 32-bit compatible DAC via USB, Lumin sends 32 bit when needed. This is verified by a third party DAC manufacturer.


Holo’s manual to the rescue, they write the May supports 32 bit …

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Right, that reminds me, Holo is using XMOS. So it probably should support 32 bit from the interface. How it processes the 32 bit internally is another matter.

Take another example, a popular DAC is marketed as a 20 bit DAC because its DAC chip is 20 bit. Its interface has to support 24 or higher bit, because the interface is either 16, 24, or 32 bit.

Ok the distributor clarified that the USB input does accept 32 bit, but the dac is 24bit, so the conversion is happening in the dac and the Lumin is likely passing 32 bit. Thank you.