Not measuring twice and buying an extra 1.0M worth of interconnects and power cords. It was compounded by the fact that I have mono blocks and two subwoofer amps and they are sited 12 feet from the preamp. That's a lot of extra cables/cords--and they are very fine (and expensive). Ouch. Wish I hadn't done that.
Your single most significant purchase mistake?
Your most significant regret for having bought? Big expectations and an even bigger letdown? The one you kicked yourself the hardest for ever having bightÂ