This could easily apply to probably any amp, but I got the C 272 along with a C 162 pre/pro to drive my Wharfedale Opus 3s a year and a half ago. I've been very happy with it, until the amp started making an annoying buzzing sound that goes on an off in approximately 1 second intervals. It's not super loud if I'm playing music at a decent volume, but I can tell it's there.
I had been leaving it on non-stop, so I started shutting it down when I don't use it, and that solved the problem for a few months. However today, it won't stop. Any other ways to trouble shoot before I consider spending the $ to try to get it serviced?