Janice & Bud,

That's very much the same way i am testing macOS Sierra.

It's installed on an external FireWire drive.

All my major DAW's as well as The Band-in-a-Box 2016 play nicely in/with Sierra.

No problems, as such, with iZotope products ( and have nearly all of them ).

Still waiting for Steinberg to do something about providing an Sierra install helper for their products ( Cubase, etc ).

What i noticed with the very last update of Sierra is that RAM available has dropped significantly. To compensate, i have disabled for example Siri and some of my add on system application helpers.

Glad you started this topic.