When I listen to an Eddie Prévost release, I often think about just how shocking this type of quiet non-jazz improvisation must have been in the late 1960s when so many of the early AMM's contemporaries were leaning into Ornette, Ayler, and their heavier followers on the continent. Certainly, the AMM has lost much of that shock value over their 57-year run. However, they have lost none of their creativity and, instead, refined their approach and vision over those decade. They might be a well-known entity by now, but they are also still inimitable. Testing, a collaborative live outing from 2004 between the early-aughts AMM core of Prévost and John Tilbury and sinewave sorceress Sachiko M, speaks directly to that.

Prévost and Tilbury have explored a wide range of sonic densities and soft layers of timbres over the years. Testing catches them on a night when they embraced their more gradualist impulses with a determination and confidence singular in its unscripted precision. Remarkably, Sachiko M matches them in these respects. Long expanses of quiet sine tones and slight noises open to passages of crisp piano notes and concentrated ruffling. Normally, sounds like this might seem incidental; in this context, they sound profound. Each draw of a string, press of a key, drag on a metal surface, and electronic crackle is deliberate. Their sparsity gives each element space and time to realize itself and decay. Nothing gets crowded and, remarkably for minimalist music such as this, nothing overstays its welcome. Instead, the single track that makes up Testing is complete and, in that sense, perfect, thoroughly and fully realized. There is nothing to add or subtract.

Another performance on another day might have sounded quite different and equally complete whether it was quieter, louder, or something else. That, however, is the magic behind the best of AMM and, apparently, Sachiko M. They convey that sense of in-the-moment perfection in a way that, really, no other improvisors in this aesthetic terrain can. In that, the title is misleading. This was no test, in the sense of an uncertainty of success. The trio might not have known exactly what the product would avail, but one gets the sense they knew it would be sublime.