What is Band in a Box? Band-in-a-Box is intelligent music accompaniment software. You can hear and play along to many song ideas and go from nothing to something in a short period of time. Band-in-a-Box is your on demand backup band. Just type in chords using standard symbols (like C, Fm7, or C13b9), choose the style you’d like, and Band-in-a-Box automatically generates a complete arrangement of piano, bass, drums, guitar, strings, etc. Then, you can play back your music with pro-quality instrument sounds. UltraPlusPak vs Pro We are often asked what the difference is between the UltraPlusPak and Pro version of Band-in-a-Box.