I presume you mean a cck-3 camera connection kit when you says a usb3 charging port device? That’s standard issue
if so the hub doesn’t power the usb hec, the hec is entirely self powered from within the helix
the usb drives are something I’ve got working after 14.x somewhere update, it’s not as clean in operation as an android device, but it does work… to expand you can’t play direct from the usb hub, you have to drag items of music to the device into something like the ho res player from onkyo and play it from the iPad, basically you can now move files from a usb device to the pad or phone
wjat you can’t do is plug a usb drive in and play files from the usb stick without moving them (that I’ve found anyway, I’m happy to be corrected on this @zippy) from memory you have to do some joggers pokery with the files app to put the desired audio content on the iPad physically
im also curious as to why you need a usb hec and a lb smsl usb bridge to get optical from the iPad to the dsp? Why not just run optical and cut the hec out of your life completely (using the usb hub before the hec may resolve someone the charging issues you get when running cck3 to a usb hec… that may actually be a thing and good for solving the usb hec issue
as for hubs, I have tried with success the ram mount five usb hub on my iPad and it did work, it also didn’t like the topping sometimes and seemed to lose its ability to play audio from the D10s, this setup also overcame the weak supply from the cck3 that has been lowered in current on new devices I think and let me plug the lightening to usb cable into the hub and into the cck3 and charge the phone from the hub as well, odd but it does work
Good effort…
ps have you compared the smsl audio quality with the usb hec and swapped back and forth?