A couple of nights ago, while listening to my system, the left front speaker sounded odd, lower volume compared to the right speaker, and scratchy. So I started to troubleshooting in trying to pinpoint which gear is acting up. I tried several sources SACD and the problem persist. And then my multichannel amp started getting into protection mode. So I pulled out the amp from the wall unit to do more troubleshooting. As I pulled out the amp, I noticed that the GLS banana plug for the LF cable had a piece of aluminum strip hanging off the red plug. As it turned out, it was the GLS label from the plug came unglued and loose. It was made of some sort of aluminum paper strip (label on one side, shiny aluminum strip on the other side). Apparently, somehow it came loose and shorten the positive to the negative plug. GLS banana plug body is made of metals, so I can see this to be the case. It could have been an expensive problem with shorten out amp problem. Who knew a piece of label could caused this? Btw, GLS Banana fins are also a problem. After repeated ins and outs, it could flatten, thus causing them to come loose. I had replaced them once on two sets with a new pairs, and the replacements had the same problem after a few months.
I have replaced the plug with Audioquest BFA Banana. Pricier but it has a lot better grip and design.
Bottom line, it's better to spend your money on better quality banana then having to spend time troubleshooting or worse yet, an expensive mistake.