I have one for our SS amp, had two made for tube monoblocks (which I generally use under the CDP now), and one for a preamp. Three of us were listening the other day, auditioning a new amplifier. After about an hour, we agreed it sounded very good, though not quite 'there', if that makes sense. We put the Neuance beneath the amp, and the first to shout out--within 5 seconds--was the non-audiophile. He said what we all noticed: that the music had a levity and energy to it that was missing without the shelf. The background was also quieter, and you could hear the blended interplay between instruments. Immediate results, and the music became far more exciting.
I hope that answers your question(s).
