TOPIC:

Bought this thing just for iPad, based solely on posts on this forum. Spent hours on this today. I am a software engineer. What am I missing?

USBStreamer B Firmware v6.B3 (ADAT mode)
iPad Pro 5th gen
iOS 15.6

Used macOS to flash latest firmware as found on website.
Used macOS Audio and MIDI Setup to set USBStreamer clock to ADAT (external)

Signal Chain:
iPad->Kingston Nucleum USB-C Hub->USBStreamer B->Presonus Quantum 2626->MacBook Pro->Reaper

I have tried SynthOne with AUM and with Audiobus3. Both AUM and AudioBus3 can see the 8 outputs on the USBStreamer B, but I get no sound into the Quantum 2626.
I have tried the exact same setup using iPad Speakers (unplug USBStreamer , and I hear sound.
I have unplugged the USBStreamer B from the iPad and plugged it into the MacBook, then used RogueAmoeba SoundSource to redirect Spotify audio to the USBStreamer B output. I am able to hear audio in Reaper from the Quantum 2626 ADAT In as expected. So I know the USBStreamer B works, and I know the Quantum 2626 and Reaper on my MacBook work. That rules out everything except iPad support for USBStreamer B.

What am I missing? It seems everything works, but when I plug USBStreamer B into iPad, I get no sound output. I can't try TOSLINK because the Quantum 2626 only supports ADAT. I have rebooted iPad several times, tried starting AUM or Audiobus3 first, then plugging USBStreamer B in, I have tried the other way around, I have checked iPad settings, volume is up. I just don't know what else to try.

Am I going to have to return this thing? Seems like a waste of time.

I had a sample rate mismatch, MacOs Aggregate Device was inadvertently set to 48, and AUM/AudioBus were both set to 44.1. I was playing around in the settings of both apps and found the rate settings. Once I set them to 48 I heard audio. I then figured out it was the MacBook driving that, so I found the setting in Audio and Midi Setup and set everything back to 44.1. Solved that problem.

However, now I hear slight pops in the high end. I did quite a bit of A/Bing to be sure. It's definitely there. USBStreamer clock source is set to ADAT. Quantum 2626 is set to internal. Just to be sure, I unplugged the USBStreamer from the iPad, and plugged in a Focusrite Scarlett and just used audio cables into the Quantum 2626, so iPad->Hub->Audio Interface->TS cables->Quantum 2626->MacBook Pro, and there were no pops. So that rules out any issues with my Quantum 2626 and the iPad. I only hear the pops when using the USBStreamer into the Quantum 2626. Any ideas?

Aww man, so bummed out. After reading several posts, it seems like the clocking for the USBStreamer just sucks. It sounds like a firmware problem. I've found several posts mentioning odd behavior, and very little responses from MiniDSP. I wish I had done more reading before buying. Another cool piece of hardware hobbled by poor software and poor support.