Issue with Upsampling

Setup: Headless win PC with Roon Core/RoonServer, connected via a network switch to a MicroRendu as the Output. Control via iPad
Hardware: Win PC i3 2100 3.1GHz, 4GB RAM, Win 8.1 Pro OS 64 bit
Roon ver: 1.3 (Build 242) stable 64bit
Size: Approx 21,000 tracks; mostly WAV files and some FLAC lossless

Issue: With the above set up, I have been able to achieve uninterrupted playback for a few days at native resolution 16/44.1 and also upsampled via the DSP engine to 176.4
Last evening, out of the blue, everytime I attempted to upsample, the track would play a few seconds and then stop. The Bright blue light would disappear and iPad controller would show an error message that the audio track is loading very slowly. I would have to revert to default resolution for it to play again. It played ok at 16/44.1. Have not made any changes to the hardware or network

Would appreciate some tips/suggestions where I might look to find the problem. Assuming that since it played (with upsampling) with the same hardware, it may be a software or network issue but would appreciate expert advice

Hello KBN, I did not see what DAC you were using in your setup. The first thing I would try is to check your Windows PC and see if there has been a recent Windows update.

The microrendu connects to a M2Tech EVO D2D converter which feeds a chord DAC via XLR
Thanks I will check for updates

So I checked and there were several Win updates which I have now installed
However, the issue persists - still can’t playback with upsampling

Actually, I think you misunderstood me. I was asking you if an update had happened which might have caused the issue and would have suggested uninstalling said update. The point was to find if a Windows update was the cause of the issue, not to install any further updates.

Oops - yes I think I misunderstood you
Anyways, before the issue started, I didn’t install any updates. Just now was the first time I installed any updates since I upgraded to 8.1Pro

Hi @KBN ---- Thank you for the report and the continued feedback. Both are appreciated!

Moving forward, can you verify for me if you are making use of any active firewalls or antivirus applications in your setup. If you are, would kindly disable these functions (temporarily) and confirm if this triggers a change in behavior.


Hi @Eric
Firewall has always been disabled from the start and no I don’t use any form of antivirus

Hi @KBN ----- Thank you for touching base and verifying that information for me.

Moving forward, I would like to gather the following information from you:

  1. Please confirm where are you storing/accessing your musical collection from?

  2. When you notice this behavior when upsampling can you please provide screenshots of:

  • Your signal path leaving Roon.

  • What CPU and RAM usage looks like.


Thanks for the follow up - sorry I have been busy hence the delay in response

  1. All music is stored on a 1TB spinning hard disk inside the same PC which runs the RoonServer (it has a separate SSD for the OS and RoonServer)
  2. I can send this to you

However, based on researching some past Community posts, I stumbled upon a post by Brian where he suggested to limit the bit length for the output device (uRendu in my case) to max 24

I made that change and it seems to work now - I can upsample to 176! I however need to verify if its stable and works everytime

What is the significance of this fix? When in Enhanced mode, is the output bit perfect and lossless?


If the DAC’s input method cannot handle 32 bit depth then you need to make sure it is sent only the highest bit depth it can handle. The different input methods on Chord DACS can have different input bit depth specs; for example, the Hugo TT’s optical input is limited to 24 bits, while the other input methods, USB/COAX can handle 32 bits.

If you are asking if there is any change to the signal, then, no. When 44.1 is up-sampled to 24/176 the bit depth is just increased by padding it with zeros.

That can be a religious question. Technically, no. Functionally, yes. Especially when you are just multiplying the resolution, ie 44.1 to 176.4. The reason the Roon team made the light just a little different and called Enhanced is that there are users who feel any change to the original signal constitutes it not being “bit-perfect”, including up-sampling.

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Thanks for the explanation and the honest response.

Hi @KBN ---- Thank you for touching base with me and sharing the results of your testing when “Max Bits Per sample” is set to 24. Very please to hear that you are now able to upsample to 176.

Let me know how things hold up!