I have owned the Placette RVC, Placette Active, K&K SB102 -I now have a Bent TAP-X which is the newest version with using autoformers -- let's just say that if you are going to try a passive it should be given serious consideration. What has also worked very well in my system context (sensitive tube amps with high inout impedance) is the Goldpoint SA-1 stepped attenuator with a list price of $312. The transformer and autoformer passives do eliminate concerns of impedance matching and cable lenghts.
