I recently installed the ARC tube rings (dampers) in both my SP-8 and the input drivers on the amp, ARC D-115 Mk2. The improvement in focus and separation of the instruments along with a dramatic improvement in dynamics is not subtle. Highly recommended. You can order direct from Audio Research (ask for Leonard)Phone 763-577-9700. They cost 5.00 per tube and there are 2 rings per tube.
