MQA via SPDIF inputs?

[Guest dr_carl]

Does anyone know why nearly every DAC that does MQA will only do it via USB input? Is there any technical reason for this restriction?

 

If I'm limited by my streamer to digital SPDIF output then MQA decoding via USB input only is not useful.

 

Please share your knowledge. 

 

 

[pwstereo]

The optical output is limited in bit depth and sample rate compered to USB. It's likely that MQA exceeds the capability of the optical output.

 

Edit, added this spec info:

"The most common SPDIF data rates are 44.1khz for stereo CD audio and 48khz for digital audio tape (DAT). The most typical SPDIF transmissions are limited to 16 bit audio due to the limitations of CD even though it is designed to support 20 bits and 24 using after-market adapters. To support transmitting signals that are less than 20 bits, the left-over bits are automatically shaved off to zero."

 

Edit 2, added the MQA info:

"TIDAL has partnered with MQA to deliver something infinitely better: an authenticated and unbroken version (typically 96 kHz / 24 bit)..."

Edited September 24, 2020 by pwstereo
Added specs and MQA info

[Hi-Fi Whipped]

17 hours ago, dr_carl said:

Does anyone know why nearly every DAC that does MQA will only do it via USB input? Is there any technical reason for this restriction?

 

If I'm limited by my streamer to digital SPDIF output then MQA decoding via USB input only is not useful.

 

Please share your knowledge. 

 

 

Your streamer if it can decode mqa will do the first unfold (think that’s what it’s called) and out via spdif as 96/24 PCM so your external Dac can receive the signal. Pretty sure you are only missing out on the difference between 96/24 and 192/24 by going down the external MQA dac method which some would say isn’t that big a deal.

[Guest dr_carl]

Thanks @pwstereo. Your response is helpful.

 

I'm not convinced that MQA is worth the bother anyway, and I'm certainly not buying another DAC just to allow it. I was merely curious as to why so many products only decode via USB input. I note the KEF LS50 Wireless II does both decode and full unfold, and there is no USB input, so its more likely to due to bottlenecks in some SPDIF implementations. 

 

Thanks also @Hi-Fi Whipped, but I already knew that much.

 

In any case, given the majority of MQA material is only accessible via Tidal, I want them to eliminate the lag from their Australian servers before I even begin to go further down that road.

[Hi-Fi Whipped]

2 minutes ago, dr_carl said:

Thanks @pwstereo. Your response is helpful.

 

I'm not convinced that MQA is worth the bother anyway, and I'm certainly not buying another DAC just to allow it. I was merely curious as to why so many products only decode via USB input. I note the KEF LS50 Wireless II does both decode and full unfold, and there is no USB input, so its more likely to due to bottlenecks in some SPDIF implementations. 

 

Thanks also @Hi-Fi Whipped, but I already knew that much.

 

In any case, given the majority of MQA material is only accessible via Tidal, I want them to eliminate the lag from their Australian servers before I even begin to go further down that road.

I wouldn't invest in MQA gear just for MQA, its sonic benefits or lack there of is well documented. I only choose to listen to MQA via Tidal when I can because I already have the gear to do it as a bi-product of choosing the streamer I did.

[wklie]

On 24/09/2020 at 12:08 PM, dr_carl said:

Does anyone know why nearly every DAC that does MQA will only do it via USB input? Is there any technical reason for this restriction?

 

This depends on where the MQA decoder runs on.  If it's running on the USB processor and the other inputs are not routed into it, then only USB gets MQA decoding.

 

Likewise, if the MQA decoder runs on the network processor, then only the network input gets MQA decoding.  This is not really a great limitation because the primary source of MQA music is from Tidal.

 

There are new hardware that is designed to decode MQA from all inputs, e.g. Esoteric K-01XD that decodes MQA CD directly.

[Guest dr_carl]

Thanks @wklie, most enlightening...and I  note that the Mytek liberty DAC decodes from all inputs...so it can be implemented if the designer wants to go that way.

[Grooved]

On 24/09/2020 at 6:53 AM, pwstereo said:

The optical output is limited in bit depth and sample rate compered to USB. It's likely that MQA exceeds the capability of the optical output.

 

Edit, added this spec info:

"The most common SPDIF data rates are 44.1khz for stereo CD audio and 48khz for digital audio tape (DAT). The most typical SPDIF transmissions are limited to 16 bit audio due to the limitations of CD even though it is designed to support 20 bits and 24 using after-market adapters. To support transmitting signals that are less than 20 bits, the left-over bits are automatically shaved off to zero."

 

Edit 2, added the MQA info:

"TIDAL has partnered with MQA to deliver something infinitely better: an authenticated and unbroken version (typically 96 kHz / 24 bit)..."

 

I don't think it's correct. Even the highest MQA file (unfolded to 24/384Khz) has around 2Mbits/s bitrate, which is less than a 24/44.1 PCM bitrate. And every SPDIF output will at least send 24/96 PCM, and some 24/192 PCM, which makes more than 2 times (24/96) or 4 times (24/192) the MQA bitrate.

In Tidal app, and in Roon, you can decide for each output if you want to decode (first unfold) or not decoding anything and send raw MQA. So you should be able to send RAW MQA over the SPDIF output, meaning you only have to link it to on SPDIF input on the MQA DAC (full decoding+rendering, not only rendering like DragonFly).
But is there a MQA DAC allowing to decode+render that signal over SPDIF ? The iFi Audio iDSD Pro looks like one, but I didn't see an example with more than 44.1 MQA file tested

Edited January 4, 2021 by Grooved

[wklie]

On 04/01/2021 at 7:05 PM, Grooved said:

But is there a MQA DAC allowing to decode+render that signal over SPDIF ?

 

A few, e.g. Esoteric K-01XD.