" ... they don't mimic the special quality of tubes -- a kind of creamy sweetness in the harmonic presentation. It is easy to understand the appeal of that tube sound; it has had a grip on me for years. But what the Spectrons do is, to my mind, ultimately even more impressive....[they] have a crystalline purity in the reproduction of every voice and instrument that sounds more to me like the essence of live, unamplified music -- which I attend, on average, more than once a week year-round-- than any other amplifier, at any price, based on any technology, that I have ever heard"
-Blue Note 2009 Award for Best Amplification by Enjoy The Music to Spectron Audio amplifier - http://spectronaudio.com/
John Ulrick of Spectron is the inventor of class D audio amplifier in1976.
Check their awards and professional reviews on their web site and do Audiogon search for the owners comments/reviews.
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Rafael