My old Sony was the same way, a nearly inaudible hiss which was always present. Coincidentally enough, my new receiver, a Pioneer, is silent when not playing anything (except on the MCACC setup screen, there it produces a very loud hiss which I can hear from my seat, odd).

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris