The absolute "best" filter/conditioner for digital

Have you tried combinations of approaches?
If you want something inexpensive Emotiva has a nice RFI filter with 6 outlets for about $120. Works very good in my system. They also have a two outlet for $99 for power amps. It does not seem to harm dynamics at all and it also besides filtering correct for DC offset in the power line
Zd542 is right on the money. The Cable Co. may not carry everything (who does?), but they carry Pure Power+, Silver Circle Audio, Shunyata, Audio Magic, Running Springs, Audience and Furutech. The heavy hitters, in other words.