Power cord to add ease and tame treble.

As Big_Kidz and The Psychic allured, you may very well be hearing what noisy untreated AC does to the sonics when the lines are not properly conditioned. But of course, everybody using electricity has dirty/noisy AC.

If you do not have dedicated circuits/lines, then you are also probably getting a double-dose of dirty AC since your digital source would be injecting much digital noise back into the AC (supposedly digital noise is bi-directional) and may very well be carrying over to the amp and/or preamp.

Even if you already have dedicated circuits/lines but no proper line conditioning, you still have AC noise coming into the house and the digital noise will still make it's way back to the service panel and then into your other components from there.

Lastly, I'm not familiar with the sonics of the interconnects or speaker cables you mention. But there are some to many otherwise decent ics and speaker cables that actually induce much grain and hash. So common is it, that this grain and hash is often times mistaken for digital hash from inferior cd recordings.

Other ics and speaker cables will minimize or eliminate this grain or hash leaving you with a much lowered noise-floor and a very pristine, articulate, and significantly improved musical presentation.

-IMO

I would agree on at least some power conditioning for your digital. Another angle would be Walker Hi Definition Links.

Glai:
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.
Luis

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.