The ZBox from MOTU is a guitar pickup impedance adapter that allows for connecting an electric guitar or bass to a computer audio interface without losing tone. Today's guitar amp modeling plug-ins are amazing in their ability to faithfully model real guitar amplifiers. However, they're missing a crucial element of the signal path that simply cannot be modeled in software - the proper input impedance of a real guitar amplifier.
The ZBox matches the output impedance ("Z") of your guitar to the impedance of a non-amp input, such as the microphone/instrument preamp input on your audio interface. Without proper impedance matching, your guitar won't sound natural or "feel right". The authentic matching circuits emulate the 2-jack switching network found on many classic amplifiers, complete with analog simulation of the input tube grid. To support a wide range of guitars, the ZBox provides authentic "Hi-Z" and "Lo-Z" inputs, just like the ones found on many classic guitar amplifiers.
The unit is not a computer-related device and does not require any software drivers. It does not even require a power source. If you use Digital Performer's Custom 59 amp model plug-in, or a third-party guitar plug-in product like IK Multimedia Amplitube, Waves GTR, Native Instruments Guitar Rig, or similar guitar modeling software, the use of the ZBox will further enhance the authenticity of the tones you play from these products.