I went from AQ King Cobra to Kimber Hero with WBT caps. I really liked the King Cobra, but the Hero sounds a good bit better in my system. My DAC (Rega) is a tad on the fuller, and warmer side, and the soundstage is pushed back a little. I found the King Cobra added to this. The Hero sounds more stripped down, cleaner, and more forward. It sounds more open and airy, and the soundstage is wider and deeper. Images actually seem a touch smaller, or maybe their sizes are truer?
System synergy is what it's all about. I'm not sure I'd like the Hero as much if I had the BDA-1. I have a B60, Rega DAC fed by Apple TV 1, and Audio Physic Yara Evolution bookshelves. My system was on the leaner side of things when I had the Theta Cobalt DAC, which is why I think I liked the King Cobra then. I liked it after I bought the Rega DAC, but the Hero sounds a good bit better now.