IC´s:Stealth Indra, Prana Cosmos or Kubala

What are you looking to accomplish or change? What are your sonic preferences? I have Kharma speakers and used to have Valhallas. Although I liked them, I found that Silversmith Palladiums and Kharmas own Enigma ICs gave me more robust sound with a richer harmonic texture and without getting muddy or overly dark sounding. It was like I was getting more "audio" pixels on my sonic screen. Now this suggestion also has to be taken in the context of the rest of my system which may be more synergistic with the cables I mention than yours might be.

I tend to echo Fmpnd's sentiments about what you're looking to change and system synergy. I can tell you, FWIW, that in my system, which has a Jadis preamp (which uses EF86 tubes and is not as dark as my previous Jadis preamp) and Lamm tubed amplification, which may be a little on the dark side compared to your amplification (no Kharmas), there was a noticeable difference in the tonal balance of the system between the Nordost Valhalla and the Kubala Sosna Emotion interconnects. The Nordost was highly detailed but ultimately lightweight in character, with a lean, taut bass reproduction and plenty of "air" in the highs but a harmonic thinness tonally in the midrange that I felt was a little unnatural sounding (but for all I know, it accurately conveyed what it was fed). In my system the Kubala Sosna is more balanced tonally, and is particularly "right" in the midrange, instruments sounding more like real instruments, with the richer harmonic texture that Fmpnd is referring to. Dynamics are about the same with each in my experience. But while I have heard both the ARC and Boulder at my dealer's, I don't have experience with them in my system, so I can't tell you how different the Kubala Sosna might sound in your system. I would note that the electronics you have are about as clean, detailed, and revealing as anything out there; if you truly like that sound you may wind up preferring the Nordost.

The two previous posters make a good point: It's very difficult to make a suggestion without knowing your sonic priorities. That said, I've had the best luck with Jena Labs' Dreamdancer interconnects and speaker cables. FWIW, I own Von Schweikert VR-9s, and the Jenas are the best match I've found for my system. I've auditioned the Silversmith Palladiums and Indras, and while they are fantastic cables in their own right, I found the Jenas to be more of a synergistic match with my gear.