Regarding copper cable quality, there are lot's of good options that make great cables....some recommendations here are UPOCC (Ultra Pure Ohno Continuous Cast), which is commonly from Neotech.....great cable.
Others to compare: OCC (Ohno Continuous Cast) RAMM Audio, DH Labs, Zavfino, Furutech, lot's of others, UP-OFC (Ultra Pure Oxygen Free Copper) Viborg and Neotech, Triple-C (Pure Copper Continuous Casting) Furutech, SAEC, and Acoustic Revive, 102SSC (special surface copper) Oyaide, DUCC (Dia Utra Crystallized Copper) Furutech, Alpha Nano (Alpha OFC + nano liquid) Furutech
I have no current comparisons for the above cables, but I am interested in the technologies. I've bought a reasonable amount of each type, and over the next year will be DIYing speaker and power cables with them. Not sure what the results will be, but it'll be an interesting none the less