I have had the opportunity to use a Placette Passive in my own system (which has evolved since purchasing it) and trying it out in vastly different system. The 2 considerations listed by Jameswei above are right on, and are of great importance when deciding whether or not to use a passive preamp / attenuator. I have found that, at least in the case of the Placette, a high gain source and a friendly (>= 100 kOhm) load at the amplifier are key, especially in the absence of impedance management circuitry and any sort of buffering (which I think would be the purist definition of a passive). In my system, which is very friendly for the Placette, the passive has been magic. In a less "friendly" system (lower output digital source and < 30 kOhm load) the results were not good. In fact, we noticed a roll off of the highs, less stable images, and rolled off bass. Thus, based on my experience I would certainly place the Placette near the top of the list, with the caveat that current system components need to be taken into consideration.
