Thread: FW 15.4a Bug?

@wklie (hi peter) I updated my U1 Mini to 15.4a and have been testing out the new ability to have a USB DAC and an S/PDIF DAC connected at the same time (switching between them with “USB/SPDIF Mode” setting) and I think I discovered a bug:

If the USB DAC is powered on but the USB/SPDIF Mode = SPDIF, the LUMIN will not do MQA Core Decoding out of the SPDIF connection (the DAC connected via SPDIF Coax displays the “folded” 44.1 or 48 kHz sample rate). When I turn the USB DAC off, the Lumin will do the core decode (2x 1st unfold) and the DAC shows the expected 88.2 or 96 kHz when an MQA song is playing (the SPDIF-connected DAC does not support MQA so I like to get at least the 2x unfold/decode).

Turning on the USB Mode and the USB DAC (which *is* an MQA renderer) and playing an MQA track works as expected and the DAC receives the decoded MQA and displays the correct MQA rendered OFS.

I haven’t tested any other SPDIF connection when the USB DAC is ON, just the Coax. Currently, I have to turn off the USB DAC or disconnect it so the the U1 Mini does not sense an active USB in order to get proper MQA Core Decode output to the SPDIF-connected DAC. I was hoping this new USB/SPDIF Mode capability was going to allow quickly switching back and forth between two DACs. Hopefully this is just a bug. Streaming Qobuz instead of TIDAL and there are no issues with bit-perfect playback and proper sample rate switching.

Cheers,
Mike

Peter, is there anything else to be aware of with this release? I went ahead with it as soon as it popped up on the iPad a couple of days ago, but I don't see release notes either on the LUMIN app or the website. I haven't noticed anything different, but I've been very busy so I haven't really looked too hard.

Originally Posted by wklie

I've sent a firmware fix to you in PM.

Please let me know whether this fixes the problem you experienced.

Thank you! I will let you know how it goes. I’m sure it will fix the issue.

I just resubscribed to TIDAL after they announced on Reddit that they are going to start offering “real” Hi-Res FLAC soon and not just MQA and their 44.1/16 stuff. So I hooked up my MQA-capable DAC again to watch how they implement this (and hopefully they don’t just repurpose their MQA stuff like they do with much of their Hi-Fi tracks). I’m guessing it will take time to get Hi-Res FLAC versions alongside the MQA tracks (I imagine they will keep both versions for those who like MQA, and they will offer a toggle in the app Settings for which version you prefer).

So switching between DACs with the Lumin app is going to be useful. Thanks for that feature.

Cheers,
Mike

As expected, this firmware fix (15.4b) solves all issues with MQA Core Decoding to an SPDIF connection while an active USB connection is present; thank you Peter! I really appreciate how fast you fixed it. Cheers man.

Originally Posted by wklie

Thanks for the confirmation. Which USB DAC model are you using?

Hi Peter, sorry for the late response. I had multiple USB DACs connected to test this. MQA DACS: Oppo 205 (with all the latest firmware), Lotoo Paw S2 dongle, and iFi xDSD.

And also non-MQA USB DACs: RME ADI-2 DAC, L&P W2 dongle, Chord Mojo 2.

Your fix worked perfectly for my main setups, with the Oppo 205 connected to the Lumin via USB for TIDAL playback, and the RME ADI 2 DAC (connected via SPDIF coax) for everything else (and my main headphone amp as well).

Thank you.