Passive Preamps

I have the EVS "Nude Attenuator" RCA version which costs $225. I didn't evaluate others such as the Placette Audio, Art Audio, etc. My preference is the type that eliminated one interconnect and mounts directly to the back of the amp's RCA. Has anyone done cross comparisons between passive preamps? I have seen passive preamps as high as $1000. My system - Sony SACD player, Harmonic ProSilway II interconnects and a Bel Canto EVo 200.2 Digital amp.