Have you guys tried Blackhole instead? It's a zero latency virtual interface. I'm using that to pipe Mainstage into Jamkazam and it's working very well. You need to set up an Aggregate device in the Audio Midi settings and use that in Jamkazam to keep getting clock sync errors and glitches, though. The Aggregate device is sort of tricky. You need to set your interface as the clock source and Blackhole as the second device and enable drift correction for Blackhole. Then in JK you select that interface and the first 2 inputs and outputs are your interface and the rest are the "Blackhole" inputs and outputs. It gets confusing but you'd generally choose inputs 3 and 4 and outputs 1 and 2 for a single stereo instrument in JK.
-Aaron
-Aaron