Hi Diki,
I use the E80 as a master because the Tyros has the speakers built on. As I said it works but with the following problems.
I can't change on the E80 when used as a master to the E80 itself. The Tyros has a option to turn midi off, the E80 hasn't. So I must turn off both boards and restart. Then when I use the E80 I can't change to master board (restart again). I know my english isn't that good but I hope you understand what I mean.
Greetings, Johan