I have long thought that to get digital to sound right you not only need a well-designed source, you also need to take lots of care of the AC (if you aren't using a battery-powered unit, of course). So, I started with dedicated lines, "audiophile" outlets, a balanced power unit (equi=tech), power enhancers from Alan Maher.
That all sounded good but I was shocked to add a Hammond choke to the mix. Using a IEC liberator cord, the Hammond gets connected at the end of the chain. Hey, for about $40 it was worth a try. While I have not listened enough to understand the full effect (I always think settle in time is needed to really assess any change), so far I'm really surprised by the positive results.
I'm assuming that what I'm hearing (dynamics, soundstage, more "tube sound" - my source is tubed) and not hearing (no noise), is actually the result of all of the above. But, the jump in enjoyment with the choke is dramatic. I have no idea why this works.