Craig, your system does in fact have line conditioning. The power supply section of your 3803 has a transformer, rectifier and filter capacitors which are designed to supply clean DC to the amplifier section; no further processing is necessary.
As to surge protection, although I've never bought one, a simple device in the $20 area might possibly be of some use. Audio equipment handles surges of hundreds of volts routinely and surges above a few thousand volts will destroy the power cord or preceding wiring before it can reach the equipment. There some chance of a surge falling into the in-between strength range and being successfully suppressed by the protector.
