Cary Audio SA 200.2 SE power amp (latest version)

@dilatante have you swapped in completely different / better shielded interconnects and different speaker cables just for the heck of it to see if anything changes?

While my SA-200.2 was dead quiet, some other adjacent components can generate this  type of low level noise you are referring to. Worth a shot if you’ve not already checked. One of my former SS amps was ultra sensitive to picking up noise like this, fwiw. Best of luck.

I'm using very well shielded interconnects and speaker cables and power cables. My speaker cables and interconnects are Cardas Clear Reflection and as all my power cables are Shunyata Research Delta NR. 

@dilatante Those should work nicely and a great match with your amp too. Nice. I had the Cardas GC and CR ic cables myself and can truly appreciate what you have there. I did have to get one pair Golden Cross reterminated once.  

So, this slight remaining hum still occurs on the right channel when the rest of the system is off, correct? Does the slight hum out of the right speaker still occur if the interconnects are disconnected and you power on the amp by itself?  And does the hum start out a little louder and quiet down after the first minute or two of power-on?  hmm.. just trying to think through it with you as you already sent it back/forth.  

@decooney 

The slight fain hum is there when all my equipments are turned on. Haven’t tried with everything else turned off but the power amp. But the faint buzz is only audible when I put my ear right up to the speaker and isn’t audible from say 2 feet away. But the other night after the amp was turned on for some 9 to 10 hours straight with playing music most of the time, and after 9 or 10 hours I noticed the buzz became a bit louder.

I had the Cary Audio SA 200.2.  I had the same buzz problem.  It was present on both channels.  It did not increase with volume.  It could be heard whether or not my Cary SLP-98P was powered up.  It was coming from the amp itself.  It could not be heard when music was playing.  The problem was once I knew it was there I couldn't unhear it, and it became bothersome.  

I contacted Cary for help.  I got this response focusing on the 3 wires connected to the PC board:

"We have learned the manufacture of these connectors used oil film coating on them for storage.  When the connectors are plugged into the board sometimes the metal doesn't make a good connection. To make a better connection we would pull the connectors off and push back on once or twice. By pulling off the connector and pushing back on the (2) metal pieces scrape and dig into each other making a very good connection. There are (2) amp modules. So one would have to do this for both channels."

I tried that.  It made no difference at all.  I eventually sold the amp.

Apart from that significant issue, the amp sounded very good.  If it weren't for that I'd likely still be using it.