The White Oak PL14_20 will replace PL14A, PL14B, PL20, PL36 (Series II) and with some chassis work the PL0171 board. Nearly all PL amps had identical topologies for the final output driver and predriver stages which is what enables this. The various boards that Phase Linear used were just refinements of the original concept created with the introduction of the PL0171 board. These refinements were for size reduction, cost reduction, modernization to take advantage of more modern components and a desire for universality across the product line (makes manufacturing easier and drives lower overall costs). The PL20 was the pinnacle of this effort on Phase Linear's part but acquisitions, etc. changed the course of events for them and this never became widespread.
Lee replaced the PL36 in Don's amp with the PL14_20 PCBA.
