Was sitting on the couch listening to the system saying to myself, I can't read any more of this book, it's too cold and windy to play golf, I don't want to turn on the TV ... why not get the cotton balls and alcohol and ! tips and clean my contacts.
I've been remiss this past year, I usually do this in the winter. So ... 2 hours later and they are all clean. But wait, there's nothing coming from the right speaker. So on the hunt I go, testing continuity in the interconnects - all fine. The amp and is OK too. I chase it down to the sub crossover I use between the amp and preamp. There's a high-pass signal pass-through from the preamp to the amp.
Opening it up I find a broken solder join. Must have bumped something when I was cleaning it, so out comes the soldering iron and all is well again.
Now I turn everything on again and sit down to listen. Crapola, this is sharp and forward. Transparent as hell but hard on the ears. It's going to take a few days to settle in I suppose.