I'm using Iconoclast 4x4 gen 2 UP-OCC balanced interconnects between my DAC and Preamp (1M), and between my Preamp and monoblock amps (7M). I love this cable. I tried a number of other cables and was never completely satisfied until I tried these.
I also tried their speaker cable, and while it was good, it wasn't an improvement over my DIY cables. A few months later, I bought a pair of Kimber KS3035 speaker cables and these were the clear winner for me.
At some point, I'd like to try KS3038 or KS6068, but for now I'm happy with the ones I've got.