Many thanks for the contributions.
dknk - my conclusion is similar, but I find my disappointment is aimed at Volumio - it seems to me that Volumio is only doing MQA passthrough, not decode - so the ifi DAC is not getting a decoded file and is therefore not unfolding it.
My testing:
I have a Raspberry Pi 4 running Volumio
I have this outputting audio via USB to an iFi Zen DAC - which is an MQA authenticated renderer.
I have Tidal (HiFi subcription) running on an iPad
-
play track on Tidal app and switch output to Volumio in Tidal connect mode.
Effect - music starts playing - volumio registers that it’s better that CD quality, but the DAC does not show MQA detected. -
play same track on Tidal app but connect iPad directly to the DAC by USB.
Effect - music starts playing - volumio is not involved - and the DAC MQA lights up to show MQA. However - using 4 USB cables and WiFi means that the track kept pausing. Need to do more testing to see if this was the cables or the WiFi - downloading the track seemed to help, which obviously suggests the WiFi -
play same track - via Volumio - direct and with no involvement from Tidal or iPad.
Effect - music starts playing and no MQA light. -
as a control - use Roon. This involves the same hardware - but with the Raspberry Pi running Roon Bridge under Linux and the iPad running the Roon app to call up a Tidal track via its own app. This time the Roon app is the decoder and it handles all the networking via its own proprietary protocol.
Effect - music plays and the DAC light shows MQA - plus the Roon app gives a full breakdown of the playback chain and reports exactly what is going on at each stage.
So - the Tidal app on the iPad is acting as decoder (this is not the case for the Tidal app on Android, as Android audio output on USB is different - I believe like Direct Show in Windows) but the Volumio app is not - whether direct or via Tidal connect.
Ie - in order to properly unfold MQA using Volumio - with the convenience of Tidal connect - you need a full fat MQA device which is capable of acting as decoder and renderer - these are expensive to the point that using a Raspberry Pi becomes non sensical.
My aim is to make no compromises on quality within reason, but maintain convenience in the sense of using a tablet for interaction.
Previously I had ruled out Volumio because I didn’t like the interface or search (which I still don’t) and was really impressed with the news about Tidal Connect. That seemed to solve all my problems.
But - it doesn’t.
I’ll still need to cough up for a Roon licence. Or - get a better quality long USB extension