Press and hold Up, Right, A & B on the 2nd controller and Up, Right, A, B, Select & Start on the 1st controller then press Reset. If done right, the sound test should appear. Use Left or Right on the 1st controller to select music and Left or Right on the 2nd controller to select sounds.
In addition, when playing the game, a debug mode will be enabled. On controller 2 press A to raise your gold by 1,000 and B to gain levels.And, finally, when you choose your name at the start of a new game, you can hold a button to go to a specific level - A for Chapter 1, B for Chapter 2, Right for Chapter 3, Left for Chapter 4, and Up for Chapter 5 (the final level).