A short solo saxophone piece can be found on the (Y)Earbook, Volume One CD (1991, Rastascan Records), which also features music from guitarist Henry Kaiser and percussionist Greg Bendian, among others.
Also in 1999, Plonsey toured the Netherlands with Steve Horowitz' Mousetrap Quartet, alongside of reed players Peter van Bergen and Michael Moore.
While in the Netherlands, he engaged in one-off improvised music concerts with The Amsterdam String Trio and trumpeter Eric Boeren among others.
Two notable CDs with John and Peter Hinds of "Sun Ra Research" fame were released on the tiny Omni Sonic label in 1994 and 1995: Connections and Another Curiosity Piece.
Before focusing on operatic composition, he was one of the leading members of the Bay Area Improv Scene, particularly during his time at the Beanbenders music venue.