When powering your ToneWoodAmp on/off, the screen shows the combined voltage of all 3 batteries. It's recommended to keep each battery above 1.2V (3.6V total) for optimal performance.
Most Alkaline AAs are 1.5V, so 3 AA batteries provide 4.5V. The ToneWoodAmp works best between 3.8V-4.5V and may experience power loss at higher voltage peaks (hard strums) below 3.6V (1.2V per cell).
For optimal performance and extended use, consider using Lithium-Ion rechargeable batteries such as the Tenavolt AA, which have no voltage drop as they drain.