I am able to pipe Logic (and Mainstage) into JK via Blackhole in a manner similar to what is described above. It has been working very well for me with no noticeable added latency.
In Logic the input device is my interface (1st Gen. Scarlett 2i2) and the output device is Blackhole. I set the sample rate for the project to 48khz. I create an aggregate device in the Audio Midi Setup app with the interface as the clock source, and Blackhole set up for drift correction, both at 48khz. In JK I select the aggregate device as the audio interface and use inputs 3 and 4 and outputs 1 and 2. If your interface has more ins and outs you'll need to select higher numbered ins since they are stacked in the aggregate device with the interface ones listed first. That's the confusing part. I also find that I need to reassign the interfaces to the aggregate device in the Audio Midi Settings app each time I run JK since I'm using a laptop (2016 15" MacBook Pro) and plugging/unplugging the interface a lot.
-Aaron
In Logic the input device is my interface (1st Gen. Scarlett 2i2) and the output device is Blackhole. I set the sample rate for the project to 48khz. I create an aggregate device in the Audio Midi Setup app with the interface as the clock source, and Blackhole set up for drift correction, both at 48khz. In JK I select the aggregate device as the audio interface and use inputs 3 and 4 and outputs 1 and 2. If your interface has more ins and outs you'll need to select higher numbered ins since they are stacked in the aggregate device with the interface ones listed first. That's the confusing part. I also find that I need to reassign the interfaces to the aggregate device in the Audio Midi Settings app each time I run JK since I'm using a laptop (2016 15" MacBook Pro) and plugging/unplugging the interface a lot.
-Aaron