Nordost's Lars Kristensen can always be relied on to give an enthusiastic and instructive demonstration, and so it was at SSI 2010. I missed the first part of the demo, but I was there for what I was most interested in: the effects of the Quantum Qx2 ($1700) and Qx4 ($2700) Resonant Technology "power purifier" devices that Art Dudley has written about. I can't say that I really understand the technical explanation of how these devices work, but the demonstration showed that they certainly do work, the sound—which without the Quantum devices was actually better-than-average—acquired greater dynamic freedom, sharper imaging, and the soundstage became more spacious.
