I don't know about the Victor 884, but the Victor 883 uses the 5V version of the
LM2931 in an SOIC-8 package. They have a PIC16F627 doing the signal processing. The mosfets on the 883 are the
IRL2203N. The high side gate voltage for the mosfets is generated by a simple
boost regulator. Op amps are used to control the voltage going to the gates.
-Ken