For the single-chip version, you need to program the ATmega328 + adjust
its fuses from another Arduino
pin 2: One of the low-power LED pins (try both ways!), MIDI
#5 (signal)
pin 7: Other LED pin, MIDI #4 (power), power to pin 20
pin 8: Ground to pin 22, 22 pF smoothing capacitors to each pin of crystal
pins 9, 10: Crystal + smoothing capacitors
pin 15: Audio out (in this case to headphone socket)
pin 20: Power from pin 7
pin 21: Not used!
pin 22: Ground from pin 8, MIDI #2 (earth - MIDI cable screen is wrapped
around this to keep it out of the way)
NB:
Handy guide to MIDI
pinouts