I haven't done the comparison but read the Placette Web site. I have owned Placette preamps & compared it to the best out there. It is by far one of the biggest bargains in high end audio. Guy is great & builds an amazing product. It is a purist approach which the Adcom isn't. The Placette is 100% transparent. The Adcom is an all together different unit & shouldn't be compared as such. If you want strictly a passive buy the Placette. If not then buy the Placette Active but it will cost.
