Classical Branca, Glenn: Symphony No. 1 (Roir A125) - ''Tonal Plexus'' is the subtitle of this massive rock toccata, described as ''music in four movements for multiple guitars, keyboards, brass, and percussion.'' It begins and ends with explosive explorations of a single note. In between comes a journey through Branca's magnificent obsession with sound for its own sake, complete with unlikely instruments, tricky tunings, and all-enveloping volume. The third movement is the strongest, with echoes of ''The Ascension,'' an earlier piece that might be Branca's masterpiece. Missing is the physical impact his symphonies have in live performance, when their sonic waves surround the listener like a cocoon. Still, the recorded version brings out details easy to miss in person. A treat for the adventurous, but stay away unless your're ready for guitars strung with steel wires and percussionists walloping oil drums. (Available on cassette only).