Made almost exactly this comparison in the last few weeks. I was running AQ Diamond x2. Tried the Golden Ref. They are very different, each with advantages. AQ - clearly more detail in highs, tighter in the bass. Cardas - unbelievably beautiful mid-range - voices are amazing, and much better depth of field. I'm going with Cardas! Equipment - Theta Data2, Levinson 360s, 38s, 333, Bryston 3B, with Audio Artistry Bethovens.