I don't know where to find a copper digital cable, but why do you want copper especially? I'm using Stealth Varidig digital cables, both RCA- and XLR terminated (S/PDIF, AES/EBU), and both beat anything else I've used, including Altis Altimate optical. 30-day money-back guarantee too. Check them out, with explanation of why they're so good, at www.interlinkhouse.com.
