PCB and parts which add 1/4" switching jacks for Audio In, Audio Out, and CV in, plus a barrel connector for DC power, MIDI In and MIDI Out jacks, and a toggle switch which allows you to change your Bank 1 sample rate clock on the fly.  This board is not sexy, but it does make your life a lot easier.  It also fits the Acrylic Enclosure perfectly, oddly enough.