I wanted to give you an overview of my testing of Roon ARC and the issues related to the load it places on the iPhone – in my case, an iPhone 12 Pro.
First, in broad terms, the problem is that Roon ARC places a ridiculous amount of load on the phone as compared to other applications that are performing an identical function. For this posting, I am going to limit my feedback to files downloaded from the phone and then played from the local copy – versus streamed. Streaming has its own set of issues, but for clarity I am focusing on downloaded files.
The load on the phone has been assessed by the temperature of the phone (very very hot) and the amount of time the phone can play from a full charge until the battery is exhausted – less than 25% of the time versus other applications. I have compared this to several other applications that do a similar function – downloading a Redbook or above quality file to the local device and then performing playback. No application is as resource intensive as Roon ARC.
My library files are ~50% Redbook (44/16) and ~50% high resolution formats ranging from DSD/DXD to 192/24 and down. They are all in FLAC or DSF format. In the case of my library, when I’ve downloaded a file, Roon ARC will ALWAYS need to resample the file as none of these are in 48/24 which is what the iPhone wants to play. I don’t know if playing a FLAC file versus another lossless format makes a difference.
The inability to download a file in 48/24 for playback using the iPhone’s playback mechanism is one source of the load. I notice extended usage times and slightly lower temperatures when I am playing a file which I downloaded into Roon ARC at 48/24. (As a work around, I’ve created a full duplicate copy of my library in which all files (>10K Albums! – 82 hours of processing time on 20 cores! multiple TB of space!) have been resampled to 48/24 and I select that version for download.)
I have observed other cases where Roon ARC uses comparatively high amounts of power to perform functions which are much more efficient on other apps. I presume this is a collection of multiple small issues rather than a single big one – if this is the case, it’s just application tuning that is needed.
Until then, please allow phone users to choose to download a version of their music file in the native sample rate/bit depth of the phone. This will be a big step in resolving the problem.