I agree that coax is best, even on RCA's if implemented properly (which is not usual). I had Wadia and Altis Altimate optical for years, but as my system got better I realized that it's the second-worst (next to Toslink). If you contact stnemo@starpower,net, he'll explain WHY optical is worse, and tell you about his Varidig technology which, uniquely, insures a proper 75 ohm impedance match. Or see the discussion at www.interlinkhouse.com. I'm using his coax, and the sound beats Altis and Wadia optical by a mile.