I use Jena Labs Twin 19 speaker cables in my system and have compared them to several similarly priced cables. Unfortunately, while I have tried Nordost SPM reference cables, which I found thinner and not as extended in my system, I have not compared them to the Valhallas. To me, the Jena's have done the best of any cable I've tried in my system to this point (hardly exhaustive) --they are quick, extended, detailed without being overly so, deep and most importantly, natural sounding. Also, I noticed references to Jena Symphony speaker cables in a couple of places in this thread. This may be a new naming scheme, but I was under the impression that the entire line of speaker cables was Twin N where N is some number in {5, 7, 11, 15, 19}. I have not yet tried the Jena interconnects.
Just how good are the Jena's? After breaking them in, I sat my girlfriend down for a listen and she grundgingly offered that the system finally sounded amazing. That was worth the $4300 right there.