With the caveat that I am new to Cubasis 3 on iOS–I would love there to be a simple answer I’m just missing–this is starting to drive me a bit bonkers.
I am having a devil of a time trying to figure out why I can’t seem to address the scratchy static that seems to follow when I try to set up an Audiobus session, wherein I send multiple Audiobus “channels” to Cubasis 3, and then in a final “channel”, direct Cubasis 3’s output to the audio interface out.
Before adding Cubasis to the Audiobus session, everything works and sounds as I’d expect, but somehow adding it also brings the static. I figured this was probably just a mismatch of audio buffer/sample/rate settings, somewhere, and I think I’ve played around with those enough to conclude either that it’s not that, or that I’m not looking in the right place in either Cubasis, Audiobus, or possibly MG3.
Curiously, MG3 does sometimes complain that its host DAW is sending “irregular audio buffers”, but I’m not sure where that might fit in the stack.
Have others run across this? If it is an issue of getting host and plugins in sync for audio settings, where is it I should look, other than checking MG3 (which defers to the host), Audiobus at the Settings gear, and Cubasis at the Setup gear?
So you’re using IAA to interface Audiobus 3 (AB3) with Cubasis 3? Is your iPad powerful enough to do that?
I just tested getting an audio stream from AB3 into Cubasis 3 and it was a very frustrating exercise that ended in failure and AB3 crashing a lot. It reminded me that I haven’t had much nice to say about Audiobus 3 since a few years back. It used to be quite a reliable tool but it somehow went off the rails. I only use AUM these days. It’s easier to use, more reliable than any other iOS host and it’s cheaper than a nice bottle of wine.
To be fair to AB3, I did successfully get configurations to load and save but it didn’t take well to loading MG3 as an AUv3. I had to use MG3 in standalone with virtual MIDI. It runs at about 50% CPU on my old iPad at a 128 buffer with Gigfast Lite running an amp sim/effects and Animoog Z running on MG3-generated MIDI. But IAA to Cubasis 3 was just never going to happen. I gave up.
Might I ask, why not just load anything you need in Cubasis? Is AB3 a mission-critical app?
First: my iPad is a 6th gen Air, M3, so I would hope it’s got the horsepower. 
And just FTR, I just last week made the switch to AUM, which I admit I’m finding to be pretty amazing. Honestly I was happy with Audiobus for quite a while (and no problems with MG3 either); the only thing that I found really annoying about it was having to explicitly pass individual CC messages on thru to each plugin that needed them. (With Circa in particular that was a PITA.) What ultimately got me to take a hard look at AUM was that Audiobus doesn’t really do “mix bus” elements at all, and I quickly realized that AUM handles those beautifully. I pretty quickly learned that AUM’s MIDI routing model completely solved the passthru annoyance as well, and in hindsight I can say that I’ve already noticed that AUM isn’t having the occasional flaky episodes that Audiobus does.
Plus, AUM’s built-in recording facility seems so simple that I’ll probably use it to record, at least at first. I’m sure I’ll wind up getting back around to Cubasis, but I want to get the live-control bits sorted out first, and then get into the details of how to use Cubasis as an end point. So, at least for the moment, that’s on the back burner again. 
