Your interface doesn't have an audio input? Interfaces that only have MIDI in/out and no audio are pretty much a thing of the past. Most newer interfaces handle both MIDI and audio.
MIDI allows a computer to record what your fingers do on the keys, even if there is no sound. If you record MIDI, then your computer can play back what you did exactly as you did it, every time, without any variance. This would include recording when the sustain pedal is pushed, when the volume is turned up and down, when the pitch bender is moved, etc.
If you also connect your keyboard's audio output to your interface's audio input, then you can record the MIDI and the audio at the same time. Then you can play back the MIDI and it will play the audio from your keyboard exactly the same way every time.
Or you can connect the MIDI output from the interface to a different keyboard and - if everything is set up correctly - the MIDI you recorded the first time will play that other keyboard's piano sound instead. Or you can route it to another synth and let that recorded MIDI play a string patch......or a vibraphone patch....or an organ patch.....etc....etc..... MIDI only tells the instrument on the other end HOW to play the sound, how to play it exactly the way you played it, but MIDI doesn't care what synth or what instrument or what sound is on the other end.
Another good concept with MIDI........ think of a TV. A tv has several channels, with a different program on each channel. MIDI is similar. With MIDI and synths, you can have 16 channels, and there is a different sound or different instrument on each channel. The big difference between MIDI and a tv is the tv can only play one channel at a time. MIDI can play all 16 channels at once. You might have piano on channel 1, synth bass on channel 2, synth horn on channel 3, synth strings on channel 4, a drum machine listening on channel 5, and a rack mount fx box listening on channel 6. If you want to play and record the piano, you set your keyboard to talk on MIDI channel 1. Then when you're ready to record a bass line you set your keyboard to talk on MIDI channel 2. Each MIDI channel has its own instrument (aka "patch"), its own volume controller, etc. You can even use MIDI controllers to control the rack mount fx like changing the delay echos in real time, or changing the reverb in real time, or turning the flanger on and off for the guitar solo, etc.
Just before I switched to computer I was using a Tascam 2488. I had my sequencer set up to use MIDI to control the 2488. MIDI was controlling the track volumes, track pans, EQ, fx, and even controlling the start and stop synchronization of the 2488. With that set up, the 2488 was basically acting as a MIDI controlled 16 track tape recorder (except there was no tape). So I recorded the analog sources (guitar, bass, voices) on the 2488 and then MIDI synched it to the sequencer that was playing back all the midi sources (keys, horns, strings, drums, etc). The sequencer was controlling the 2488, the midi synths, and all the black boxes in a 7 foot rack. I had a special box that could create 4 banks of midi, each bank with 16 channels. So I had 64 MIDI channels available at all times.
MIDI is worth learning.
I'll still look into MIDI, but as far as actually recording the keyboard goes, would using a mic be my only option? Could I run a cord from the Keyboard's headphones jack right to the interface?
