I was using a Joule Electra LA-100MkIII before moving to a passive TVC. THe TVC was built for me by Kevin Carter at K&K Audio using S&B TX-102 MkI transformers and Seiden switches. It is configured with dual volume and dual input selectors. It has 2 inputs and 2 outputs.
The Joule is a very musical and outstanding preamp. However, the passive TVC just matched up better with my high input sensitive solid state amp. I gained more accuracy, detail, and overall tonal balance with the K&K, at the expense of some mid range sweetmess and the musicality the Joule offered (which for a tube preamp is pretty neutral IMO). I don't regret the move, but I do miss the Joule.
I have never listened to the Placette, but have heard the Sonic Euphoria as that was on my list. The K&K is better IMO and has character (there is a liveliness to the presentation), which I think the Sonic Euphoria lacks (somewhat boring presentation, but accurate). I did listen to some resistor-based passives and prefer the TVC implementation. Again, more of a preference as I heard quite a few nice resistor-based passives. To me the TVC is easier to match up with amps and you don't necessarily have to worry about cable lengths.