I think our posts crossed in-transit, but here are my quick thoughts:
1) If I understood your posting correctly (I’m reading this on a portable device so I may have overlooked/misunderstood some detail), you obtain good quality sound when the **powered** USB hub is in the chain: is that correct?
2) If so, that’s precisely what I encountered when my phone’s Lightening port was hooked into an Apple branded connector-->Jitterbug-->DragonFly-->Etymotic and when this device chain was run from iPhone (11) battery power. However, when the phone was plugged into a wall socket, all this worked properly. That was my first clue that this was a power issue.
3) If it’s the case that the DragonFly powered up properly but no sound without a powered USB hub, to me that suggests your earphones are drawing too much power for the port to supply.
4) If I’m wrong and your earphones work after an initial run-through with the powered hub and they continue to work *after* the powered USB hub has been removed and the rest of the set-up is plugged into the Lightening port, it may be the case that iOS is somehow re-setting. If that’s what’s happening, it’s a possibly a new security feature: iOS 10.13.x has a built-in setting used to defeat snooping hardware (e.g., Cellebrite’s famed/infamous hacking device). With the phone powered on but if the user doesn’t permit access, the Cellebrite gizmo can mirror the contents when plugged into the Lightening port. Apple blocks that attack once the phone has not been accessed for some (arbitrarily chosen) time: about an hour, last I read, but that may have been revised.
KAC
1) If I understood your posting correctly (I’m reading this on a portable device so I may have overlooked/misunderstood some detail), you obtain good quality sound when the **powered** USB hub is in the chain: is that correct?
2) If so, that’s precisely what I encountered when my phone’s Lightening port was hooked into an Apple branded connector-->Jitterbug-->DragonFly-->Etymotic and when this device chain was run from iPhone (11) battery power. However, when the phone was plugged into a wall socket, all this worked properly. That was my first clue that this was a power issue.
3) If it’s the case that the DragonFly powered up properly but no sound without a powered USB hub, to me that suggests your earphones are drawing too much power for the port to supply.
4) If I’m wrong and your earphones work after an initial run-through with the powered hub and they continue to work *after* the powered USB hub has been removed and the rest of the set-up is plugged into the Lightening port, it may be the case that iOS is somehow re-setting. If that’s what’s happening, it’s a possibly a new security feature: iOS 10.13.x has a built-in setting used to defeat snooping hardware (e.g., Cellebrite’s famed/infamous hacking device). With the phone powered on but if the user doesn’t permit access, the Cellebrite gizmo can mirror the contents when plugged into the Lightening port. Apple blocks that attack once the phone has not been accessed for some (arbitrarily chosen) time: about an hour, last I read, but that may have been revised.
KAC