I agree the Golden Refs are very synergistic with the Merlins (at least with the interconnects and reportedly the speaker cables as well). I am currently using the Synergistic Signature 10 (top copper cable in Synergistic lineup, single run with the Cardas jumpers). These give a very lively sound, very detailed as well, really don't lose much here to the Synergistic Resolution Reference (silver wire). However, I agree that silver cables may not work with the Merlins, all the Synergistic top of the line and the Ridge Street Poiemas were a little cool/analytical in my system.
I have tried both the PAD Venustas and Dominus (still use the Dominus digital cable) interconects in my system, for whatever its worth I prefered the Cardas Golden Ref, just a little more continuous sounding.
Another contender at a relatively low price is the DIY VH Audio CheLa speaker cable, a multi stranded copper cable as Bobby recommends. These are a bit warmer than the Synergistic 10's, mucho detail, organic and rich sounding, I'm still breaking in and evaluating the sound on these.