White noise when playing non 16bit / 44100Hz tracks

Roon on Mac Mini USB-> Mcintosh C48 preamp/DAC

I have a few AIFF files that are 24bit or 48.000Hz and above, all stored in a external drive connected to a Mac Mini that runs Roon.

The Mac Mini connects via USB to the digital input of my Mcintosh C48 Preamp/DAC. Every time a non 16bit/44100bit track comes up in a playlist I’m listening to, I get loud white noise. I can’t figure out why.

Is there any setting on the Mac Mini or in Roon that I need to check?
Thanks in advance for your help.

Hi @Luca_Grelli,

Does this same behavior occur if you play to a different endpoint?

Can you share a screenshot of the Signal Path when playing to this device, as well as a screenshot of device setup?

Actually no. I have a Bluesound powered speaker as a second endpoint and it works fine. So it must be how the C48 DAC handles higher bitrates and sample rates. I see that you have a C48 in house? My firmware is V 2.10-2.10. It’s in theory supposed to be able to handle up to 192. So not sure what it’s doing wrong.

Does turning Enable Integer Mode off have any effect?

no effect.

Ok, I stumbled into the DSP settings, and enabled sample rate conversion to max PCM Rate and now all the higher sample rate /bit rate files work. The signal path says Enhanced, which I’ve never seen before. Here are the screenshots. Is this an optimal solution or am I losing something by using these settings?

Optimal is what sounds the best to you, but, imho you are not losing anything by doing a Sample Rate Conversion. I have no problems with upsampling and do it all the time (that is why you are now seeing Enhanced since the stream has been upsampled from the original rate).

Personally, I use Max PCM rate (Power of 2) so that all calculations are kept in the same resolution family. Which would change your Sample Rate Conversion from 88.2 to 176.4 (and even multiplier). Sources that are 48 (or 96) will go to 192 (as that is an even multiplier).

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