I to have a STR-555ES and bought it new in 2000. It worked fine for about a year, then it failed to power up at month 13 or so. Turned out to be switching relay that went bad.... I have had the same problem (power up...dead unit) now five other times in the past five years. I figured that I obviously got a lemon unit, as my other friends units (same model) has worked perfectly during the same timeframe....I don't play loud music or 'push' the unit at all. Mostly I keep the unit on with one of the satellite jazz stations on. every now and then, I shut the unit off. This condition only happens when I attempt to power the unit on. It is now a boat anchor, not even good enough for a garage room amplifier for 8-tracks.