After further testing it seems that the CEntrance DACportable simply doesn't like multi-tasking, i.e. playing music And going online. It also seems happier with the old USB2 Lightning to female USB type A adapter..
I have just listened to two and a half HiRes albums, each about an hour long, in a single playlist, with the Onkyo app converting the different high bit rates to "High Quality 5.6MHz DSD". It had one minor problem (a crackle and pop) during the first change of format (352.8kHz Wav to 88.2kHz Flac) but then handled the next change (to 48kHz wav) without so much as a pause! I deliberately left my phone face-down to avoid overheating since the DACportable is strapped on the back of my iPhone 7+ which definitely helped - it is only just what I'd class as "warm", and the 2+ hours of continuous playback and DSD conversion used 10% of my phone battery (73 to 63%), while I noticed the DACportable - which had already been playing for a couple of hours beforehand - go from the full 3 battery LED's to 2 at about the time it made the change from the second to the third album! So, playing at a fairly high volume through my IE8's for 4+ hours used less than half its battery.
My conclusion is that while this combination of iPhone 7+ and DACportable may be a bit sensitive, it's also very efficient, and the sound quality which I haven't really mentioned before, is excellent! The soundstage through any of my 'phones is wide and clear with decent imaging and a pitch black background. Vocals are clean with no hint of sibilance, and the bass is punchy, not weak or bloated - everything is just as it should be! The only shortfall is found when trying to power my HE-560's, although even at maximum volume the sound was still crisp and clear.
A final word of advice for anyone using this device is this: If the music stops playing and / or you experience crackling, hold the power button down until it switches off (if it hasn't already), then again to turn it back on, press pause on the music player app and then press play to get the music playing again. If the sound quality is very poor and the DACportable is very warm, switch it off and leave it off for a few minutes to let it cool down. It doesn't take long and should play as normal when you turn it back on. I hope that helps. Despite its quirks this DAC/amp is really growing on me! I will certainly keep it for the foreseeable future and hope that CEntrance are able to provide the promised cable to go directly from the iPhone's Lightning socket to the DACportable's micro USB input, because at least some of the problems I've encountered are definitely due to movement where the cables join, and in the sockets. Don't discount this little device!
