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Felix, thanks for the tip on IRTrans. You're right, this solution isn't cheap, especially when it would be doing very little.
Some alternatives could be:
* ZephIR $50 USD, includes software and IR transceiver. This is a very old product however, and it's unclear how well it works in OS X. I even got an email back from the developer with example Applescript to tell it to output certain IR commands.
* LIRC cost varies, but this is a Linux thing. There's an OS X "port" but it's a hack: http://people.inf.ethz.ch/mringwal/lirc/
This would require a lot more work!
Some more thoughts about using Mini to control everything else:
1) Assuming such an IR blaster type gizmo worked well enough and could be "taught" the IR codes for the devices it should control... and assuming that this device had some usable software that ran in OS X... then it *could* be possible to use it with Remote Buddy.
2) This mystery application could be added to RB's list and a custom behavior could be created, such that you invoke it when you want to control those external devices as the TV and Amp.
3) The biggest downside to this approach that I can see is button count. The elegance and simplicity of the Apple Remote is in how few buttons there are. But (in most cases) I need *all* those buttons to control the app that's running.
4) Hence, to also control the volume of my amp, I would have to invoke RB, switch to the mystery IR program, activate that behavior, then click the plus or minus button. Not a big inconvenience, but that's the only way I can see to retain the buttons for multiple functions.
5) The alternative would be to change the global behaviors of two buttons for volume up and down to the mystery app. But then you lose two buttons!
Just thinking out loud...