Sustain without compression ...a common suggestion because it doesn't mess with your attack. The Amptweaker PressuRizer compressor accomplishes this in several unique ways, and includes a built-in output FET limiter/booster, making this a powerful clean tone tweaker. Using parallel studio-grade compression with wet/dry blend, and some unusual side-chain variations, it varies from smooth compression that limits the initial 'whack' to a dry-blended approach that adds compression after a short delay. The PressuRizer is designed to work for both guitar and bass. Since many always leave their compressor on, the PressuRizer has a cool 2-Step footswitch....normally it's a true bypass on/off switch, but if you press & hold the switch, it locks the compressor on, and then tapping kicks in another boost knob on the side of the pedal.