Question on U1 and U1 Mini

The U1 or U1 Mini look like good options for my Roon playback as I have a lot of money invested in external DACs. I have a few questions:

  1. Are both USB outputs able to be routed to separate DACs? I need to route USB signals to the input on my Marantz SA-10 internal DAC (for use with my headphone amp) and also to the USB input on my Kii Control for my Kii Three speakers.

  2. Are the various digital outputs selected via app or are they all active simultaneously?

  3. Is a more detailed manual posted anywhere other the QSG on the website?

Thanks!

  1. No. Only one USB output is active despite the presence of two USB ports.

  2. The AES / BNC / RCA / toslink outputs are all active if there is no USB connection to a DAC. You may turn them off individually.

  3. I’m afraid not. But since you use Roon, the most important thing (in addition to connecting the network cable) is to find the Lumin in Roon setup for Roon Ready audio devices, enable it and assign it a zone name.

Thanks Peter! Are all the other digital outs deactivated if one of the USB outs is used? If that is the case I will have a problem as I need to output to 2 DACs.

Also, the USB outputs do not need to be active simultaneously. I just do not want to swap cables. Can I connect the 2 USB outputs to different DACs and have them individually work when the other input’s connected DAC is switched off or not selected? Or barring that can I connect one of the USB outputs to one DAC and the coax output to the second? Either option would work for me, but I need to work with 2 separate DAC connections with only 1 active at a time.

Finally the U1 specs state 2X USB. Are both USB outs active on that unit? It is really beyond my budget at the moment though.

U1 and U1 MIN behave the same regarding the outputs.

If a USB DAC is connected, all the other outputs are invalid or off.

When two USB DAC are connected, if and only if one of the DAC is truly powered off (not standby, not just switched to another input) and cannot be detected, then we know for sure the other DAC will be used. Otherwise it is not known which DAC will be used, and it cannot be chosen.

If you want to have more than one DAC being operational without manually changing cables or toggling DAC power, please connect them via AES / BNC / RCA / toslink (all are active unless configured to be disabled) only, not USB.

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Thanks Peter - that is really helpful! I think I can work within those constraints. Any chance to make the USB outputs selectable with a firmware update, or is it a hardware limitation? The USB inputs on both of my DACs support the highest resolutions so that is driving my desire to use both of them.

No. We never meant to support more than one USB DAC, so it is auto detected and no need to be selected.

OK thanks. I know my use case is likely unique :slight_smile:

@wklie -

I intend to feed 2 DACs via a Mutec-3.

I want to feed the Mutec-3 with AES out of the U1 Mini and then feed my DACs with USB and COAX out of the Mutex. Of course, the DACs’ outputs will be into a pre-amp.

As far as the U1 Mini is concerned, will that be a problem?

Thanks

I assume you mean the MC-3+USB. If you only stream up to PCM 192kHz and DSD64 (DoP) from the U1 MINI, AES connection to the MC3-+USB should be ok. For higher than these rates, it won’t be possible via AES.

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Yeah, got lazy when I posted. I’ve had the Mutec for about a year, mostly for its ability to change formats and to simultaneously output to multiple ports.

Currently, I either run bit perfect or let my iFI Pro upsample to DSD1024 or 702/768, depending on my mood.

The DAC I’m going to pull the trigger on is a PrimaLuna Evo 100, which is only good for DSD128(DoP) or 192/24. So no real problem with the U1’s AES output.

Wanted to follow-up on my earlier question. I received my U1MINI and am pleased to say it works perfectly in my system. With both DACs connected to the 2 USB outputs the U1MINI only outputs to the one in Roon that is powered on. The other unit can be in standby without issue. Exactly what I was hoping for with no cable swapping needed! The U1MINI also sounds SIGNIFICANTLY better in my system than directing the USB outs from the Roon Nucleus+ directly to my DACs. Overall very happy with the upgrade. I need to start a U1 upgrade fund :slight_smile:

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A question for you,

  1. I found when playing Hi-Res files that when the volume of my dac/preamp is low I hear a lot of noise to even distortion, now I have been able to solve this by setting the Simple Rate Conversion to Enable in Roon, I find this strange.

  2. Is it disadvantageous to have the Lumin U1mine connected to the dac/preamp with both AES/ EBU and USB or should I not do this?

  1. If this happens with both AES (USB disconnected) and USB (AES and others disconnected), please consult with your DAC manufacturer. What DAC (Atoll?) and what target sample rate are you using?

  2. When using U1 MINI AES output, please disconnect USB first.

The strange thing is that it only happens with hi-res (24-96) and / or mqa files

That’s indeed strange. Please try the various outputs of U1 MINI individually (with unused output disconnected). If it’s still the same, please connect the DAC to the Roon Core directly, bypassing the U1 MINI, see if it still exhibits the same issue.

I don’t think I have the necessary cables at the moment. I will soon talk to the dealer, maybe I can take other Atoll Dac300 and listen what it does