The absolute "best" filter/conditioner for digital

I agree with Zd542 about trying things out, but in lieu of other information, such as your budget and what you're trying to accomplish, I always recommend the "first do no harm" approach of Shunyata. They have something for just about every budget and their gear has maintained incredible re-sale value over the years...which should tell you something.

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
Alan

PI Audio Uber BUSS.

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.

Dedicated lines...most bang for the buck. Otherwise, Audio Magic