MQA Playback & Support


#21

Now it’s showing Lossless signal path, and not MQA

Swapping the Dragonfly back in, it goes to MQA…


#22

Another swap and the MQA is back… with the xDSD.
Gamma Ray Interference?

Note there is an audible difference - in volume - higher with MQA. The rest is subtle, but there. I think the Stax are a good choice to listen for the sonic differences.


#23

You want to make sure you create specific “devices” (Audio Zone) so that Roon can talk directly to each of the DACs in question. Once you’ve done that, and they’re properly configured, you shouldn’t see any more issues with MQA periodically not working.

As a general rule, the only time you want to use the “System Output” with Roon is if you’re actually using the host-computer’s speakers or headphone output. When you have a dedicated DAC, then you should always create a device/audio zone for it and then select that as your “Audio Zone” in Roon when you want to use it.


#24

That is exactly what I expected.
I think there is hope that this may change in Bluetooth version 5.0. A2DP https://www.bluetooth.org/DocMan/handlers/DownloadDoc.ashx?doc_id=303201&_ga=2.79886487.181554813.1540251009-402207398.1531070576
describes the specification for audio streaming, and it supports at least 44.1 and 48 kHz streaming, with suggested support for higher bitrates. I am not technical enough to be certain that I am reading it correctly, but I don’t see that it would not support a non-lossy streaming transport mechanism.


#25

Unfortunately there is a lot more to this than what sample rates are supported by Bluetooth AD2P CODECs. Even 128 kbps MP3 can do 44.1 kHz sample rates. There are just FAR fewer effective bits per sample getting encoded than the constant 16-bit requirement for a lossless stream - which is required for MQA.

A much more important factor is the reliable data-rate, which due to the constantly changing bandwidth available on any Bluetooth connection (due to myriad factors including external interference, implementation efficiency, relative antenna alignment, etc.) means that even the 700 kbps or so required for a FLAC-like lossless encoding cannot be guaranteed over Bluetooth (even 5.02).


#26

I would have expected that over typical shorter ranges that Bluetooth 5 would permit data rates significantly higher than 700 kbps. What about the use of a dual connection? Maybe we’re getting beyond MQA playback and support, and this might be better moved to Wireless headphones or similar.


#27

In theory, in perfect conditions, it can do a theoretical 2 Mbps. In real world use, and with real-world devices, even with them sitting right next to each other, you generally won’t get that. And what you can get will change constantly.

That’s before we get into a discussion about CODECs.

LDAC, the best available Bluetooth CODEC has quality/reliability options … intended to deal with this exact problem.