We spoke to Kirk Hammett and his KHDK partner David Karon recently, and the first pedal we're getting to grips with is fittingly the Metallica man's signature overdrive, the Ghoul Screamer.
The GS is designed to be a more versatile take on the Tube Screamer, and with all switches up, it delivers a classic TS-808 tone – cutting bass and boosting mids.
Hitting the bass switch engages a full bottom-end, and flicking high brightens dark humbuckers, but without getting muffled or shrill. Meanwhile the body switch gives the upper mids a boost and fattens your overall tone.
The compression switches open up further versatility still: one is your standard TS compression, two is a glassier voicing, while three kicks in a tight, biting rock tone – crank up the drive for instant AC/DC and Blackmore thrills.
But the Ghoul Screamer is designed to boost a distorted valve amp, and here it really wails.
Set the pedal to low drive and maximum volume, and the body switch adds definition, while compression mode three provides an aggressive attack that's a quick fix for helping gained-up palm muting and leads to cut through.
It's rare to come across a pedal quite so instantly gratifying.