Paul and Hansang, no the pre-amplifier doesn't create any sonic signature in competently designed units; its 12-15dB of gain is an even simpler technological task than that of the amplifier. As to the processor section, of course any feature such as tone controls, ambience processing, room equalization, etc., whose purpose is to change the sound will do so when turned on. But that almost never is what those who claim to hear sonic colorations in different receivers are talking about. The claim, without factual support, is that there's some mysterious inherent audible characteristic which usually would have to involve a substantial frequency inaccuracy(e.g., the "bright" Yamaha and the "warm" Marantz), independent of any processing feature chosen by the user. Unless there're substantial measurable differences there can't be audible ones, and there aren't.
