Get closer to your sound. The LD Systems HPA1 Headphone Amplifier lets you hear your monitoring in superb detail in the studio or on stage. The HPA1 lets you mix XLR and aux signal sources together easily as the main and jack inputs run in parallel ideal to take backing tracks band mixes or click tracks from different places and combine them in your monitor mix. The HPA1 can achieve operation times of up to 12 hours when used with a good quality battery so you can keep it in use for several sessions before needing to replace the battery. An included limiter also keeps your signals clean by preventing clipping and will also protect your ears from excessive volume levels. The input signal can be heard in stereo or mono modes and switching between the two is achieved with a simple push of a button.