Audiogon member Tom_nice has Quad ESL 63s driven by tube amps and a resistor-based passive volume control. I've heard his system several times and think it sounds fabulous. You should contact him if you have specific questions.
TVC's, in my experience, are more sensitive to the source than the amp. If the source has an output impedance (Zout) less than 200, has a Vout higher than the sensitivity of the amp and is DC coupled, there shouldn't be a problem.
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