My goal was to use the Clarett and Scarlett for 16 input tracking, and to use the 2i2 as a volume knob and audio out for my big studio monitors.
I had all these interfaces setup for a session to live track a band. I had the Clarett connected via Thunderbolt to a Mac with Logic Pro X, and the 18i20 set in standalone and connected ADAT in & out to Clarett ADAT in & out (all worked and sync locked). Then on the Mac I created an aggregate audio device with the Clarett/Scarlett combo and added the 2i2. Set Clarett as clock source for aggregate in Audio MIDI setup. We had clicking, crackling or pooping noises that made it into the recordings. We tried to mess with the bit rates, sample rates, changing the clock source and other stuff, but still had the noises end up in the recordings.
I didn't have time to troubleshoot it fully while everything was there and hooked up, but I'm wondering if maybe I could have hooked it up differently.
I'm guessing I should not have created the aggregate setup on the Mac, and just used the Clarett/Scarlett combo to the Mac. Then I could have used the two Clarett TRS outputs 1 & 2, patched them to inputs 1 & 2 on the 2i2, then used it to control the volume to the monitors. Does that sound correct to anyone?
Bit late but....
1st : I guess the combo is correct when connecting 16 inputs. I found out that combining multiple interfaces or interfaces with vitual ones is asking for problems.. At least in the way you did it.
2nd : if the interface like the Scarlett or clarinet have a main out which can be controlled with a volume knob why bothering feeding that signal to a 2i2?
If you have multiple outputs for playback / recording then I understand you like to have a stereo mix somewhere in the line.... But without an external mixing board you always loose a few output ports ( 2) connecting a 3th interface will not solve your problem...
Because it is basically the same.
Can you tell why you like to do that? I know you want to control your speaker system but like I mentioned earlier the main interface can do that too.
It's not about what you got to use but how you use what you got.