Lumin U2 Mini DSD 256 Upsampling

Recently upgraded from a U1 Mini to a U2 Mini, and I thought I would try the DSD 256 upsampling that the U2 Mini offers. I went into the app and set every single DSD and PCM input rate to DSD 256 output. I happened to be listening to a 192kHz hi-res PCM download at the time and when I hit play all I got was TONS of static. I hit pause immediately but the static continued so I hit mute on my amp. I then tried DSD 128 and got the same result. However with 44.1kHz Redbook CD material it upsampled to DSD 256 just fine.

Anybody know why the higher sample rate PCM wouldn’t upsample to DSD 256? My DAC is a Bryston BDA-3 and I’m connected to the U2 Mini via USB. I did a bunch of switching on the fly between PCM 44.1kHz and DSD 256 and I really couldn’t tell any difference, so I guess for my particular DAC upsampling is not beneficial. Still curious why I had a problem with the 192kHz material however.

By the way, if anyone with a U1 Mini is considering upgrading to the U2 Mini, I can recommend it as I found the U2 Mini to offer a definite sonic improvement over the U1 Mini (at least with my DAC - your mileage may vary).

Lumin only does integer upsampling. So 48kHz / 96kHz / 192kHz are upsampled to 48kHz based DSD+ rates.

Your DAC only accepts 44.1kHz based DSD rates such as 2.822MHz, 5.645MHz, 11.2MHz.

Your DAC does not accept 48kHz based DSD+ rates such as 3.072MHz, 6.144MHz, 12.288MHz

When using Roon, turn off Lumin re-sampling. Use Roon DSP Engine then you can avoid the 48kHz DSD+ rates that your DAC does not accept.

3 Likes

Peter, thanks for the quick and detailed response! I figured there was probably some simple reason like this. I was hoping to use the U2 Mini to do the upsampling to DSD 256 as I have a basic (non-plus) version of the Nucleus and having it upsample to DSD 256 takes up most of the CPU power. I will experiment further though now that I understand the situation. Thanks again for your superb support!

When using Roon DSP Engine to upsample to DSD, turn on Parallelize Sigma Delta Modulator.

What is this setting for?

If off, Roon uses 1 CPU core in Roon Core to do PCM → DSD conversion for this step for a single playback zone. If on, it uses 2 CPU cores for this step.