Lumin U1 MINI upsampling anomaly w/McIntosh DA2

@wklie (Peter Lie)

Hi Peter - would be interested in getting your perspective on this. First let me start off with the good news - last week I worked directly with a Lumin support engineer who had the team fix my problem by creating a beta firmware update for the U1 Mini. So, thanks to the engineering team for the quick turnaround on a solution.

The problem was whenever I tried upsampling any of the Hi-Res files from Qobuz, the built-in DAC module, DA2, in my McIntosh C53 amp, while capable of DSD512, would display the PCM kHz equivalent of the DSD and all that could be heard was hissing and barely a whisper of the song being played. However, when I would play downloaded DSD files stored on a thumb drive plugged into the Lumin, my preamp would correctly display DSD & size, and it sounded glorious.

After installing the beta firmware update, either DSD64 or DSD128 now displays and it sounds good. But after playing around with it for another week, I’ve noticed some anomalies. Even if I have upsampled the Qobuz file to DSD128, the McIntosh “most of the time” will display DSD64. But then… occasionally, it will display nothing - just a blank line. And even more occasionally, it will actually display correctly, DSD128 - and this can be from any Qobuz file size but the most recent time it displayed 128 was when a 48kHz file was playing. I contacted support again and they said it is probably just cosmetic and as long as it sounds good there’s nothing to worry about.

While I’m very thankful the beta now allows me to hear files upsampled to DSD, the inconsistency still bothers me - would you happen to have any ideas? I assume there might be something going on with the Lumin handshaking with McIntosh’s DA2 DAC. (specs on the DA2 are on the web, but it’s a Quad Balanced, 8-channel, 32-bit DAC with USB native playback of up to DSD512 and DXD up to 384kHz.)

–thanks, Jimmy

@wklie will get Peter a bit quicker perhaps but he might not be getting this for another 8 hours or so as he is on HK time zone.

No. If there were handshaking issues, your music playback will be distorted or have other audible anomalies.

If there is no audible anomaly but only the display is sometimes not expected, this means the sample rate is outside the display expectations, or the display module has other limitations / issues.

Previously we have already established that the DA2 display is not prepared for DSD 64+ 3.072MHz or DSD 128+ 6.144MHz when upsampled from 48kHz-multiple by Lumin. These are not standard rates so not every DAC will support it. I agree with McIntosh - please do not worry about cosmetic issues.

And since you’re on Roon forum, I assume you use Roon. In this case, please set Lumin custom Re-sampling to Off, and use Roon DSP Engine to upsample instead. Roon will give you standard DSD64 2.822MHz and DSD128 5.644MHz, so you will have less display issues this way.

Ok - thanks @wklie for the explanation. I guess I didn’t realize there’s a difference in DSD64 or 128 when upsampled versus native. Another issue probably related to this is if I’m listening to something upsampled to DSD, and let’s say the DA2 displays DSD64, I then switch the song being played to Native or some other PCM variant in the Lumin app, the DA2 will correctly display the kHz size; however, if I switch back to DSD upsampling again, the display will remain locked on the last kHz size played. In order to get the DA2 to display DSD again, I have to delete the album from the Lumin playlist and reload it again.

Anyway, as Lumin support said, and you have confirmed, just cosmetics, really, so I won’t worry about it. But are you able tell me this: if I have selected to upsample a Hi-Res file to DSD128 via the Lumin app, and the DA2 displays DSD64, am I really hearing DSD128 as selected, or am I hearing DSD64 as the DA2 displays? In other words, who do I trust - Lumin or the DA2?

P.S.: I actually am not using Roon as I only have a few downloaded DSD files - I mostly listen to LP’s and CD’s. I’m just getting into Hi-Res files. Roon does not make an application for people like me who do not have a digital library, but just stream Hi-Res files through either Qobuz or Tidal. It would not make sense for me to invest in a NAS server, etc. to run 24x7 to host their core just so I could use their metadata while using Qobuz. The reason I posted here was because this was the only way I knew to reach out to you. I created an AudioShark account a few days ago, but never received the confirmation email, so I joined here with an account I created when I joined the Roon free-trial.

Thanks again for the quick response and explanation.

–cheers, Jimmy

With Lumin upsampling to DSD:

44.1kHz/88.2kHz/176.4kHz -> DSD64 outputs DSD64 2.822MHz

44.1kHz/88.2kHz/176.4kHz -> DSD128 outputs DSD128 5.644MHz

48kHz/96kHz/192kHz -> DSD64 outputs DSD64+ 3.072MHz

48kHz/96kHz/192kHz -> DSD128 outputs DSD128+ 6.144MHz

You’re hearing DSD128. Please check that you’re seeing this display problem only when upsampling from 48kHz/96kHz/192kHz, not when upsampling from 44.1kHz/88.2kHz/176.4kHz.

Since the DA2 display module does not recognize the DSD64+ 3.072MHz or DSD128+ 6.144MHz, the result of the display is undefined.

probably better you post here then

@wklie Ahhhh… ok - I finally get it now. Thank you for explaining it this way - it all makes Perfect sense now and I conducted a few experiments based on your figures and the behavior is exactly as you explained. I’m glad to know and understand what’s happening and why - very logical based on your fine explanation. I’ll spread the word to any other McIntosh owners that may have similar concerns. Thanks again Peter for taking the time to explain it in a way I could understand.