The chief characteristics of the Topaz are an almost completely uncolored midband, a superbly extended, tonally and pitch-correct response into the bottom octaves, and a soaring, grainless treble that captures the signature air of a recording's venue like few other amplifiers I know. Such a description does not bear much resemblance to a typical single-ended triode amplifier, and indeed, the Topaz does not seem, even on extended listening, to be an SET at all.