Hi DHo and welcome to one of the most friendly forum on the Internet.

I would get a Digital Keyboard that has both audio and MIDI outputs. That way you would have the best of all worlds. You could practice, play out, or jam with friends without lugging your Mac along plus you could input MIDI via the keyboard into your computer to include those sounds when using the Mac.

These are a few items I am naming off the top of my head that you may need in the future:

1-good near field monitors for your computer. Computer speakers are really lousy for music creation. With good monitors you can hear every instrument clearly.

2-If you are going to record you and/or your friends you will need an audio interface, one that will record MIDI and audio simultaneously. Remember RealBand comes with Band-in-a-Box and it is a 48 track Digital Audio Workstation. That means you can have 48 different instruments/sounds playing at the same time. The number of inputs you will need on your audio interface depends on how many you will be recording simultaneously, i.e. guitar, bass, vocal, keyboard etc.

3-If playing out you will need a good PA and possibly a keyboard amp.

4-If you are going to record vocals you will need a good mic AND an audio interface. Computer mic inputs are extremely bad for recording. DO NOT buy a USB mic!

5-If playing without the Mac you may need a keyboard amp. You could start out with no amp and headphones if your keyboard has headphone outs.

If I can think of anything else I will let you know.

The above is just my opinion and others may or may not agree.

Basically what I am saying is that you have to build you studio based on what you want to do, both today and what you think you will need in the future. But you do not have to build it all at once. A keyboard and BiaB/RT can last a while as you relearn you playing skills.

I hope this helps and good luck!

Whenever I get something stuck in the back of my throat, I dislodge it by drinking a beer.
It's called the Heineken Maneuver.

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware