I have not used a TVC, but did have a Placette RVC and Placette Active at one time. I think Roger's Pot-in-a-Box with 30-year old + Noble potentiometer actually sounds better than the Placette RVC. I am curious about the transformer based passives, but I do wonder why Roger who can build whatever he wants thinks that is not the best approach, especially with his amps. I have to assume that a transformer must add distortion to some degree compared to pure passive volume control, and that it must be less than linear across the frequency spectrum, most notably on the extreme highs and lows - but I'm no engineer. I do know that with my source, short run of Cardas GR (super low capacitance)and both Roger's amps and my CAT JL2 with high sensitivity and high input impedance I have a pretty ideal set-up for a pure passive set-up. I'm not sure that a TVC might not be subtraction by addition in my case. I'll say if you have a RM10 or 9 and you have not tried a passive volume control you owe to yourself to try it, no matter what active linestage you are currently using. And if you are on a budgetm I can't imagine a much better entry level system than a Pot-in-the-Box matched to a used RM10.
