Mac digital limits and Audirvana?

Hoping for some clarification regarding my late 2015 iMac (5K model with 3.2 core i5)

I’ve read in various places that the physical limit on the USB port is 25/96khz and 24/192khz on the optical out. Is this really true? Or is the limit of playing iTunes through those ports?

If I go under the my Audio Midi Setup control panel, I see much higher limits depending on what is connected. For instance, with my spdif/usb controller plugged in to the USB, I see up to 24/384khz shown.

Does Audirvana bypass these limits somehow?

I’m currently contemplating getting a long-run USB to replace my current setup of sp/dif in order to give my dad more upsampling, but not sure if it’s worth the effort.

A knowledgeable answer would be greatly appreciated.

The limited sample rates you are referring to only apply to the internal DAC of your iMac. When you attach an external DAC via USB (or any other topology, like products that convert Ethernet to USB before your external DAC), then the sampling rate is only limited by the DAC’s architecture to which you are sending data.

There’s one more limit. Core Audio, IIRC, won’t do 768k PCM or DSD512, but is limited to sending 384k PCM or DSD256 max to an external DAC.

This is true, but fortunately, it appears DSD256 and DXD (24/352.8k PCM) is where the commercial action is on hi-res, with hardly any content available at rates above this. Even if 768k PCM and DSD512 take off, there will be Mac options through products like the microRendu from Sonore which I am now using with Audirvana to achieve DSD256 playback with my Mytek Brooklyn and Mac mini.

Thank you for your replies.

My new Pro-Ject Pre S2 does indeed say it is receiving a 384K PCM. My older DAC did not give any feedback which led to my question about mac limits.

By the way, I’ve read of 16’ feet being a limit for USB. Not true. I have a 50’ (has one repeater) that operates flawlessly, except that it will not provide adequate power to the ProJect. No problems, however, using the wall wart.

Hi All,

Thought this post was relevant to my situation so here goes:

I am using a Simaudio 280D DAC which has the capability to natively handle DSD256 - However, I don’t seem to be able to configure to or get files to play at this rate - my DAC seems to drop down to 24/352.8 - Any reason why this may be happening? I am using a Mac Mini with Mojave OS with 16GB of RAM.


I know exactly why. The highest DSD rate macOS can support through core audio is DSD128 because you are using DoP within Audirvana (your only choice via USB, by the way). To do an end run around this and let your DAC reach its potential of DSD256, you’ll need some hardware and software help. I chose a the Sonore microRendu because it supports native DSD to DACs and does not require DoP within Audirvana because it acts as a DNLA endpoint. Anyway, invest in this little box (which sounds incredibly better than via USB anyway!), and you’ll start enjoying DSD256 playback with your DAC right away.

Thanks for the feedback and clarification. I did’t realize this was a Mac limitation :open_mouth:

Well, I am glad to know it’s not an issue with my DAC at least. I don’t have that much DSD256 to worry about at this stage, but I appreciate the suggestion of the workaround. For me, it’s not worth the additional investment right now and I hope that this gets addressed by Apple sometime in the future…


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