Love to do a shootout. What passive do you suggest that is transformer based?
In response to both yours and Shakey's comments I will say this. I have had an S&B MkI TVC and loved it (replaced a Joule Electra LA-100 MkIII and Cary SLP-98). However, I have to say the autoformers offered by Dave Slagle that are now used in the new Bent Tap-x are superior. I purchased a minimalist version of the Bent using Dave and John's new Slaglemam modules. It's not pretty, but sounds great and replaced a Jeff Rowland Capri in my system.
I used to also think that the transformer models were superior to the resistive models. After hearing a Lightspeed Attenuator in my system that uses opto-couplers with a resistor I'm not of that opinion any longer. Since I own both types direct comparisons were easy.
While everyone talks about impedance matching, etc. with passives, and that is important, let's not forget the role the actual attenuator switch plays. Using quality attenuator switches (Seiden, Shallco come to mind) is important in passive designs and influences the sound IMO. However, the Lightspeed attenuator is the only design I have run across that renders the attenuator switch irrelevant.
Bill - if you're interested in checking out an autoformer let me know. I might be able to let you borrow mine for a bit. Email me offline if interested.