Accuphase are second to none in their reputation for build quality and durability, as you note. However, buying from a second-hand shop you typically have no information relating to how the piece has been used or maintained over twenty years. $6K is a lot of money to spend and you might consider that the same outlay will get you a top-flight piece new with warranty, or late-model used. It's usually between 20 and 30 years of age when components first require substantial attention, though this varies of course. There's no denying that the C290V is a seductive piece.