So here's something I'm having a hard time finding. As a musician, I have a stomp box board. A lot of my effects are digital and reprogrammable. I'd love to to just "keep them all connected" to a usb hub, then connect a single usb cable back to my phone or computer.
When doing so, I instantly introduce ground loops. MIDI gets around this by having opto-isolation as part of the spec, but MIDI-over-USB of course negates this. I would love to have a USB hub that was opto-isolated for both power, data, and ground!
USB isolators (single port) can be bought cheaply on eBay but may be bandwidth limited. They use a small isolated DC-DC brick and a USB isolation chip, probably with internal isolation capacitors to get the signals across
I think the ADI ones are actually based on transformers.
Specifically they'll do "Full Speed" 12Mbit, but not "High Speed" 480Mbit. USB3 @ 5Gbit can also be isolated, as it uses separate send/receive pairs. But that doesn't mean you can use a hub and drop down to 480MBit - they're separate data paths.
If you need 480Mbit, the best solution is probably a Raspberry Pi or other SBC, to convert to ethernet.
How does one optically isolate power and ground? You can do it electrically with a transformer, but I haven't heard that optical power transducers (or something) could fit on PCBs. Yet.
Oh wait; solar calculators. Ok, but those won't give you 15W per port in any sort of reasonable size device.
When doing so, I instantly introduce ground loops. MIDI gets around this by having opto-isolation as part of the spec, but MIDI-over-USB of course negates this. I would love to have a USB hub that was opto-isolated for both power, data, and ground!