Using the Balanced +4dBU Line level via XLR is the definitive best choice for getting the highest quality results when recording an electric guitar using the WPGI.
The WPGI has 3 main applications:
1. Impedance matching: The guitar output is a high impedance signal. Most audio input loads are incompatible with a guitar directly plugged in. Therefore the WPGI transforms the signal suitable for most common audio input stages. Extensive care has been taken to preserve the guitar tone and provide the highest-quality signal to the DAW audio input device.
2. Converting an Unbalanced Signal to a Balanced Signal: The guitar signal is conducted over two wires only. The signal is unbalanced and thus more prone to picking up noise and loosing fidelity. The longer the cable, the more loss and signal degradation you will experience. The WGPI converts the signal to balanced, allowing you to run longer cables with better sound quality.
3. Pre-amplification: The custom circuit goes beyond Impedance-matching and balancing. It provides amplification to common Line level input. The on-board amps are especially selected for recording the clear, undistorted guitar signal. Thus, they don’t replace the sound of a dedicated guitar tube preamp, but instead allow a transparent neutral signal path ideal for further processing and re- amplifying.
Waves Guitar Tool Rack User Guide.