Originally Posted by Imperatore
That's crazy considering I been adding and changing speakers, gear, setup and cables like 2-3 / month for the last 7-8 months.
Wow, wow, wow.
With so many wires and separate appliances, absolutely the problem can be anything from cross talk, to inductance to EMI, to RFI, to a cornucopia of problems that I'm completely ignorant of. That being said, absolutely, yes, there can be expected low level hissssssss in the speakers. I touched on this when I commented about noise floors. And as pointed out by others (agreeing with them), being encouraging in my next, if it's low level and doesn't interfere with your listening pleasure, go with the flow as you'll only end up breaking the bank and still have to pay for time in the funny farm. As harmful as this may sound, sometimes one just has to accept imperfection. What one fails to grasp, what humans perceive to be imperfection, really is perfection and we're applying a false or pseudo standard to the outcome.
(unless design specifications to the otherwise, if a hammer falls squarely on a flat, polished piece of 0.125" flint glass from ten feet and the glass shatters, that's perfection as it's expected for the glass to shatter. not necessarily desirable but definitely expected)
It reads like you have a lot happening behind your system and you've put a lot of time, effort and thought into your setup and that in of itself can be part of the noise problem as the new addition was the straw that broke the camel's back or, yes, as you pointed out, something can be going bad and the failure is showing itself by back-feeding the noise into your speakers. Again, for all we know, it could be a neighbor's A/C unit or a refrigerator's compressor motor next door causing the problem. Maybe the transformer on the utility pole is getting a bit wonky.
As to turning the system on and plugging and unplugging cables, yes, it's understood, one doesn't "hot swap" cables and yes, the more complex a system, the more complex the switching and the turn-on procedure. As to ground loops, yes, based on your above, you definitely have a problem, waiting to happen. That's not to say you've done anything wrong, it's to say that the speaker noise was/is "potentially" a problem waiting for the right conditions to present themselves and finally, the problem has shown itself.
Working with you, I'm hesitant to add an Emotiva, XPA-5 to our system, just because of the problems the additional wires can add to our system but in the meantime, if I don't add the outboard amplifier, as you pointed out, I won't be able to take benefit of the additional amplification; headroom.
Damned if I do, damned if I don't.