It is very important, tap on any tube with your system powered up and you will hear the ringing clearly in the speakers. I haven't seen anything I would consider highly effective but maybe others know better. Even an O-ring around each tube is better than nothing. The constrained-layer damping sheets probably have the most potential. A thin layer of viscoelastic damper covered by a thin sheet of aluminum, could be cut to size with a scissors and wrapped around the tube. I'd like to know if anyone has tried this, and what the results were.
