The Palmer DUETTO is a compact active mixer designed primarily for electric guitar applications, though it also performs well with other instruments and line-level signals. 

The DUETTO enables the mixing of two active sources into a single amplifier input, with each input featuring a volume control for easy level adjustment. This device is commonly used by guitar teachers who wish to practice with their students through a single-input amp. However, its versatility allows it to function as a cable driver, mono merger, and recording preamp as well.

Thanks to its low power consumption, the DUETTO can operate on a 9V battery, allowing for extended usage. Additionally, it includes a DC input for connection to a power adapter.