Can i also use the instruments of mainstage in Logic Express9 (EVB3 etc.)?

No, they are not plugins in the sense that they can be used in other applications.

I don't know very much about Logic Express (I have Logic Pro), but the plugins (EVB3, ES2, ecc..) are shared, so you can use them in Logic, too!!

So, yes, you can use them in both programs (and in GarageBand, too, FYI)

Hope I've helped you!

=Luca=

LogicExpress doesn't contain those instruments and as mentioned before they're not plug-ins. You can use a trick to control them from Logic Express. You can create MIDI tracks and use IAC (inter-application channels) busses to route the MIDI from Logic to Mainstage. IAC can be activated in the MIDI window of the Audio MIDI setup Utility.

If you don't like this, you might consider buying Logic Pro.

Best,

DaCaptain