Fairly good assessment IMHO. Naturally that is a custom transformer, just not the high-voltage range that a normal tube amp requires. Looks like the physical

Fairly good assessment IMHO. Naturally that is a custom transformer, just not the high-voltage range that a normal tube amp requires. Looks like the physical layout might have been originally designed to be fully equipped for high-voltage operation, which would mean two additional audio transformers would be needed in addition to a high-voltage version of the present power transformer. Transformers are probably the most costly components to the BOM. The PCBs would all be different too, and a hobbyist having the proper transformers could discard the present ones and completely rewire for conventional high voltage operation, probably easiest on a point-to-point basis without bothering to design an alternative HV PCB for the proper passive components needed. If HV transformers were ever originally involved I could imagine the supply of the HV units ran out before the supply of tubes & sockets. Therefore it could have been redesigned as a solid state amp more cost-effectively using the tubes mainly for decoration and to maintain a premium pricing cache. Especially if full tube amps were originally issued and gained a decent reputation to begin with.