N_Cook wrote:

Before wrapping up a Mackie SRM450 powered speaker I took some
representative DC voltages on the complementary pair power devices of the
bass driver amp, for me and all else, future reference.
-42, -88, -42.8
41.2, 88, 42
What would the circuit type/ class name be, for this sort of biasing?

Class G or H. It's supply switching to reduce dissipation. Done it myself.
Big amps may have 3 rails.

Graham