Danny/GR Research helped me upgrade and better tune an old set of Epos ES12 speakers a couple years ago: new crossover parts, wiring, sound deadening material. Solid core wire worked great. I also have solid core speaker cable/wires from the amp, "Anticable" brand I think. Compared to a couple other set of cables I own (older Cardas and Silver Sonic bi-wire sets) the solid core Anti-Cables sound the best (marginal, but noticeable).