For those who switched to Apple and recognized, that the DigiTech GNX4 Guitar Workstation doesn't offer a lot under Mac OSX, don't give up on this multi effect monster.
Now this is what i figured out about garageband:
Mac OSX recognizes the audio I/O via USB when you connect the GNX4 to your mac, so you can record with garageband. The only thing that appears strange to me is that you can't operate on input levels. But anyway, here are the steps i made, to get it running.
1. Open Audio and MIDI setup from the application menu.
2. Switch on the DigiTech GNX4 and connect the USB cable.
3. You will immediately see the GNX4 appear in the MIDI setup and in the Audio setup tabs.
4. Select the Audio tab and select the standard input to be the GNX4's Stereo 1/2 input.
5. Open garageband and create a new track, that will be a "real instrument" track.
6. From now on you can record via USB.
Those were my steps to get it running and it works pretty well.
Now about the input volume control! My effects were modified to be used with a bigger amp, so i really had them pretty quiet. One solution to become louder on the input is just to turn up the master volume when editing the effects needed for your records. Another possibility is to turn up the volume after the track was recorded (but we don't want to do that, since we want to jam along and hear what we play ).
That's it. If somebody knows more about DigiTech GNX4 + mac, contact me in any case. I don't want to sell this device since i am quite comfortable with the effects AND I DON'T WANT TO USE WINDOWS FOR RECORDING MY TRACKS .