“It just involves moments where we both shut up for a second”: Two legends of fretless bass, one whip-smart genius shredder – here’s how the mind-blowing Testament x Pestilence fusion project Quadvium came together

Bass legends Steve DiGiorgio and Jeroen Paul Thesseling pose with their fretless basses in this promo pic for new fusion project Quadvium.

The genesis of Quadvium – the extreme fusion project from fretless bass guitar visionaries Steve DiGiorgio (Testament, Death, Sadus) and Jeroen Paul Thesseling (Obscura, Pestilence) – dates back to the mid-’00s, with the two slippery rhythm-stringers excitedly talking shop after meeting at a European metal fest.

They quickly developed a bond, and over the years – whether reconnecting in their respective home bases in California’s Bay Area or the Netherlands – they started toying with the idea of forming a fretless fraternity to transform the game forevermore.