This was a wonderful performance by four outstanding Norwegian musicians playing acoustically with no PA or electronica. Led by pianist, harmonium player and composer Christian Wallumrød, they created soundscapes that defied easy categorisation.

The quartet played from sheet music, but Wallumrød's compositions were also a framework for improvising organically in the moment. Sometimes we got electronica without the electronics as when Wallunrod’s harmonium evoked memories of the BBC Radiophonic workshop, and one of several duos was a rich conversation between Wallumrød playing toy piano and percussionist Per OdvarJohansen.

Mostly the music was quiet. Per Odvar Johansen cajoled, caressed, tapped and bowed but never crashed any part of his kit. Trumpeter Arve Henriksen played trumpet with a saxophone reed, made it sound like a flute and sometimes just breathed quietly through his trumpet in total contrast to the blast of trumpets playing Beethoven I heard spilling out of the Sheldonian as I walked to the Holywell.

Music this quiet, with small changes in pitch and rhythm and little melody, can be so cool it can bore. Not so tonight. The Ensemble drew you in and then kept you off balance. Nils Økland's Harddanger fiddle brought a dark edge “'nerves being shredded” say my notes. With everyone just tapping their instruments them with their fingers, I heard the sound of a snowpack cracking just before an avalanche. Another piece echoed Arvo Part’s spiritual music and then a New Orleans funeral marching band. Another opened with Henriksen's trumpet evoking the Muslim call to prayer and became a Norwegian folk tune.

The Holywell was totally seduced – there was an audible sigh of pleasure after several of the pieces. My only reservation was not criticism but a wish for these superb musicians to have had a full-on blast. But that would have been a different concert. This one, on a score out of five, about a seven.