Faint buzz in speakers

+1 For having the router too close to the power amp.

In fact, it is so faint you have to place your ear right up against the cone to hear it.

@jmfinney As @yoyoyaya and @herman have pointed out, there's nothing wrong with the amp. With most speakers and most amps, if you put your ear against the driver you'll hear something and its not unusual that one channel might be quieter or have a different noise floor from the other.

I recently had a (new) noise suddenly appear in my system. Quite noticeable from the listening position, it did not get louder with the volume. I checked multiple outside and inside lights, as a while ago, my dethatched garage lights were the culprits. I found nothing and upon checking my power conditioner, I found my plug had come loose and was hanging out a bit. I secured it and no more noise. I guess RF was getting in through the exposed prongs.  

@giantsalami - loose connections of all kinds can be major culprits in buzzes and noises. That incudes the breaker box where vibration can loosen the connections. WARNING to all - do not go sticking screwdrivers into your breaker box - get an electrician!

@atmasphere @russ69 - You described my concern perfectly. I will simply enjoy listening to my kit & not worry about the faint hiss anymore. Yes, the router is in a less than desirable location, however, I'm stuck with that. Even tried a faraday bag. No change. When router is completely disconnected & all breakers, except for dedicated 20a feeding my gear, the very faint hiss is still there. No change. The link to Upscale's explanation of signal to noise ratio seems spot-on. As I mentioned before, it is not audible from listening position 8ft away. Thanks to everyone & have a peaceful & enjoyable holiday!