Power cord to add ease and tame treble.

My system comprise of a Ayre CX7; Hovland HP100; Pass X150.5 and JMLab Diva Be. All IC are Cardas GoldRef, SC are Ridge St Poeima. The IC & SC were chosen after extensive in home comparo.

The sys sound pretty good but there is slight brightness, nervousness at the treble. The resolution is excellent. I have tried trivista DAC which warmed up the sound but lost sig. detail, front to back spatial clues. A friend's Cary 303/100 fits in between and is quite nice. Is there a way to tame the treble while preserving the details & reolution using a power cord?
Post removed 
I would agree on at least some power conditioning for your digital. Another angle would be Walker Hi Definition Links.
You mentioned that side walls do have curtains, does the treble quality worsens if you open them while listening?
Also do you have any treatment in the front wall, what's between your speakers?
If front wall is too reflective or have furniture in between speakers, that could be a contributing factor to what you hear. If this is the case try placing a blanket between speakers in front wall /furniture to find if this is causing you trouble. What happened? A deeper soundstage might be a pleasant bonus in doing this.
Your feedback.
JMCgrogan. I have not tried the golden ref speaker cables. How do they sound?

There is nothing betw the speakers. There is a fireplace and i am not allowed (family) to put cloth on the front wall.

What constitue proper AC filtration?

Thanks guys. Special Stehno & bigkidz.

Bigkidz, I will definitely try your method. Not much to lose.
They (Cardas Golden Reference) add ease and tame treble. I just mentioned it because it seems that's what you're looking for a power cord to do.
I do agree with the others that dedicated lines are a good place to start. This added a blacker background, improved imaging and solidified bass in my system.