butler amps havegotten rave reviews all over the web. Here's an excerpt of one review here on Audiocircle: "Musical, warm and dynamic and that sums it up, this is actually a 5 channel power amp, but its too good to be wated on AV, bi- amp your speakers Previous designs generally employed vacuum tubes in impedance-isolated preamp or pre-driver stages. BK Butler's Tube Driver BLUE technology places the triodes exactly where they should be: DC coupled through the output power devices to the speakers. Therefore, the tubes are positioned to naturally and actively respond to the dynamic speaker load. This also completely eliminates one of the most inefficient and non-musical components in a typical tube power amplifier: the Output Transformer.
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