Eldartford, you bring up a very interesting and astute point. The Legacy Focus speakers I run are so efficient (at least 96db/watt) that I can always hear hiss if I stand next to the speakers. (It's inaudible at my listening position - even to my 16 year-old daughter.)
Changing amps changes the noise, but nothing else has affected it since I took the ARC LS2B pre-amp out of my system. (The LS2B was clearly audible in the noise.) An isolation transformer on the source components (a PS Audio PowerSonic) has no discernable effect. (I was hoping it would, actually.) I recently hooked up a pair of cheap JBL mini-monitors I use for video (just for grins - I wanted to see what expensive amplifiation would make them sound like) and the hiss was inaudible unless you put your ear up to the speaker grille.
Changing amps changes the noise, but nothing else has affected it since I took the ARC LS2B pre-amp out of my system. (The LS2B was clearly audible in the noise.) An isolation transformer on the source components (a PS Audio PowerSonic) has no discernable effect. (I was hoping it would, actually.) I recently hooked up a pair of cheap JBL mini-monitors I use for video (just for grins - I wanted to see what expensive amplifiation would make them sound like) and the hiss was inaudible unless you put your ear up to the speaker grille.