Hello Lance,
Great post. I also heard Sanders amp (not in my own system) and I am under impression that they are indeed "bright". I looked into their web site and I can see that they use (in moderate amounts)global negative feedback which, according to Simon Thacher from Spectron:
" Negative Feedback
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Additionally, when an amplifier has difficulty in delivering required power peaks, other forms of distortions will occur. For example, in transistor amplifiers the increased current drawn by speakers will cause a small voltage drop across the source--i.e., the amplifier itself--which will heavily contribute to the unpleasant so-called "transistor sound. In that regard, regulated power supplies can be extremely helpful. Many transistor amplifiers use global negative feedback to reduce distortions and widen the bandwidth. The crucial factor in negative feedback is transit time, the amount of time it takes from when an error is detected at the input until it is corrected at the output. For example, a typical transistor power amplifier has three primary sections: a low-noise high-gain differential input stage, feeding a differential-to-single-ended conversion driving a high-current output stage. Each of these three stages is designed for low distortion and noise, but those attributes typically come at the sacrifice of speed. The typical transit time of linear amplifiers is about 2000-3000 nanoseconds, which is too slow for effective implementation of global feedback and error correction. This lagging results in ringing artifacts and enhances odd-order harmonics which are particularly annoying to the human hearing (5) so even the smallest amounts of these distortions are highly noticeable. Long delays in feedback also introduces transient and phase discrepancies, susceptibility to transient overload and vulnerability to disturbances at the output such as reactive speaker interactions.
In contrast, many switching amplifiers don't use low-distortion circuits. Instead, they use much faster digital logic circuits. The Spectron Musician III transit time is 200 nanoseconds. Such an ultra-short transit time allows the amplifier to correct for many small errors; and the control loop can follow the input much more accurately. These characteristics result in a more detailed, transparent sound with less noise and louder yet cleaner musical reproduction. "
This may or may not be explanation... particualrly on the background of Spectron SET magicial midrange.
All The Best
Rafael
