Recommendation on IC's and speaker for this system

You might try all copper cables, anti-cables are a "cheap try" and some people swear by them, Cardas are very good also. Give yourself a little time to adjust to the "laid back" fuller sound of copper.
What tubes are you using in the LS-8 and what cable are you using between the transport and dac?
I had a monster power conditioner in my H/T system the sound improved when I removal it (your better off with nothing).

wow, it's hard to imagine that system is bright... could the monster power unit be restricting your low end or something?

if it were me, i'd try plugging stuff into the wall for a bit just to make sure it isn't doing something to your sound. on paper, your system would seem to be a very nice, warm system.

that being said, the least bright cables i've heard are van den hul carbons (the first and second model lines of interconnects). samhar's suggestion of anticables is good too (i have the speaker cables myself and to me they do sound better than many vastly more expensive cables), but they aren't the easiest to use as they are thick, solid-core wire.

I have Kimber Silver Streak between DAC and Pre-Amp

I have the stock Sovtek tubes in pre-amp that AR put in upon last refresh which was 7 years ago, i probably need new tubes

interesting about the anti cables

I think before you change anything else you need to replace those tubes and hear their impact on the sound my guess is your in for a pleasant surprise!!! If you have the funds get some Amperex 6922's or 7308's. JJ Tesla and even Electro- Harmonix would be an improvement IMO.

I agree with the Kimbers being bright, at least for my tastes and my rig.

One IC that I find more musical and still priced reasonably (esp. used) is the Acoustic Zen Wow. I also use AZ Satori speaker wire that I like those a lot too.

I second changing tubes before anything else. Those were not good 7 years ago, and certainly no better now. Amperex is a good choice