Re: U2 Xmos Xu208 USb to spdif convertor

[Michael Larkin]

I'm new here and am hoping this is the correct forum for discussing the U2 Douk Audio XMOS XU208 USB to spdif convertor.

I bought this device for around £50 about 7 weeks ago and have been very pleased with its performance - miles better than the Behringer UC202 I was using before.

I don't use it for streaming, but rather for playing FLAC files ripped from my CD collection, but one could also use it for streaming I suppose. It's specially useful if one wants to use a PC or laptop with only USB output to feed a standalone DAC/amp with an inbuilt DAC (the latter applies to me) with spdif inputs.

I've tried to find out what the device is supposed to be doing and why it sounds as good as it does, but have had no joy. I conjecture that somehow it does power cleanup and possibly signal re-clocking, but maybe not. Does anyone know?

Also, it seems to be able, once one has installed the supplied drivers, to offer upsampling facilities in steps as far as 24-bit 192K -- I've checked this by hooking it up with a Topping E30, which registers whatever I select for the sampling rate in the device's settings in Win10, so it seems to be pukka.

It's hard to say whether the upsampling makes much of a difference. Maybe, but it could just be placebo. Has anyone tried upsampling (in multiples of 44.1K, which is what I've tried, or of 48K), and if so, what do you think?

Cheers, Michael

 

[Paul7777x]

I’m pretty sure the Douk doesn’t upsample anything.

It just passes through what your W10 machine sends it (following significant re-clocking)

Any improvement in SQ through the dac and amp, is possibly down to better jitter rejection than the Behringer. The Xmos standard is exceptionally high.

Also, using an optical cable, assuming you are, kills any noise from the laptop before it can hit the dac/amp.

 

[Michael Larkin]

I’m pretty sure the Douk doesn’t upsample anything.

It just passes through what your W10 machine sends it (following significant re-clocking)

Any improvement in SQ through the dac and amp, is possibly down to better jitter rejection than the Behringer. The Xmos standard is exceptionally high.

Also, using an optical cable, assuming you are, kills any noise from the laptop before it can hit the dac/amp.

Thanks for the reply. WRT your saying it doesn't upsample anything, I'm wondering, when I select a given sample frequency in windows settings for the driver (say 176.4 Khz), and have attached a Topping DAC (via optical/coaxial spdif) to the Douk device, why the Topping also displays 176.4 Khz on its display panel? And why it does likewise for all the different options shown in the driver's property box on Win10?

Is it that the Topping picks up the relevant values just from the driver and plays at 44.1 Khz regardless? Not saying it doesn't, only that I find it puzzling why that should be so.

Also, I'm interested in finding a reference to anything that describes the XMOS standard and what it does -- do you have a link, perhaps?

TIA

 

[Ugg10]

The easiest test for upsampling is to set your PC output to 16/44.1 (or lower if there is an option) and then see if the dac picks it up at any higher rate e.g. 24/96. If so then the XMOS is upsampling, if not it is passing it through. Then change the sample rate on the PC to different values and see if the DAC changes as well, if it does again the XMOS is passing it straight through and the updampling is going on in the PC.

 

[Michael Larkin]

The easiest test for upsampling is to set your PC output to 16/44.1 (or lower if there is an option) and then see if the dac picks it up at any higher rate e.g. 24/96. If so then the XMOS is upsampling, if not it is passing it through. Then change the sample rate on the PC to different values and see if the DAC changes as well, if it does again the XMOS is passing it straight through and the updampling is going on in the PC.

Oh, right. So my laptop may be doing the upsampling rather than the Douk? Never thought of that.

 

[Paul7777x]

Oh, right. So my laptop may be doing the upsampling rather than the Douk? Never thought of that.

That’s the thing. My older version of the Douk does the same.

As a rule it’s better to select (in windows) whatever sample rate the copy was done at to send to the dac through the Douk.

 

[Paul7777x]

This is useful. But it’s pretty dense indeed.

XMOS whitepaper - Real-Time Digital Signal Processing on the xCORE-200 architecture

View online and download XMOS whitepaper - Real-Time Digital Signal Processing on the xCORE-200 architecture

www.electronicspecifier.com

 

[Michael Larkin]

That’s the thing. My older version of the Douk does the same.

As a rule it’s better to select (in windows) whatever sample rate the copy was done at to send to the dac through the Douk.

I'm learning a lot on this thread! ;-)

Can you tell me why it's better in general to use the 44.1Khz (and very occasionally for a few Chinese CDs I have, 48 Khz) that the CDs from which my FLAC files were ripped were recorded at? I kind of intuitively sensed that it might be the case, but if you know why exactly, I'm all ears...

 

[Michael Larkin]

This is useful. But it’s pretty dense indeed.

XMOS whitepaper - Real-Time Digital Signal Processing on the xCORE-200 architecture

View online and download XMOS whitepaper - Real-Time Digital Signal Processing on the xCORE-200 architecture

www.electronicspecifier.com

Thanks very much. I'll check out the reference straight away.

 

[Paul7777x]

I'm learning a lot on this thread! ;-)

Can you tell me why it's better in general to use the 44.1Khz (and very occasionally for a few Chinese CDs I have, 48 Khz) that the CDs from which my FLAC files were ripped were recorded at? I kind of intuitively sensed that it might be the case, but if you know why exactly, I'm all ears...

Simply because Windows is not renowned for its audio capabilities. So the less it does to the signal, the better.

With digital, while it’s not really considered damaging to alter the original signal (digitally), I cant see any reason to do so.

 

[Michael Larkin]

Simply because Windows is not renowned for its audio capabilities. So the less it does to the signal, the better.

With digital, while it’s not really considered damaging to alter the original signal (digitally), I cant see any reason to do so.

Paul, you're a sterling fellow and have helped me a lot. Props to you!

 

[Michael Larkin]

And Ugg10, thanks to you for giving me the realisation that Windows might be playing a role in upsampling. I'll check out what you suggested later, but suspect that it isn't the Douk doing the upsampling. I feel like an idiot for not thinking of it before.

 

[Paul7777x]

Paul, you're a sterling fellow and have helped me a lot. Props to you!

Welcome anytime Micheal.