" The Q-10's by comparison just open up the sound more and seem to peel away a layer of "cloudy glass" so to speak. I don't know how else to describe it. The Creek, Rega and Vandys are all on the... well, let's just say not bright sounding by any means, so perhaps the clarity factor of the Q-10's evens everything out?"
The laidback sound you're talking about is most likely due to the passive line stage in your Creek. Another cause can be setup. If you don't set your speakers up using the formula in your owners manual, the drivers won't be properly aligned to your seating position, and it almost always sounds rolled off in the highs when this occurs. That, and they're not supposed to be too far apart. 6.5 to 7 feet apart from inside edge to inside edge. Properly setup, the images will go beyond the outside edges of the speakers. Also, set the contour adjustments to 0 and only use them as a last resort.
As far as speaker cables go, Vandersteen is special. They need to be double biwired. You need to run 2 separate pairs of speaker cables. If price is a concern, go to Best Buy and pick up a spool of AQ zip cord. Just as an example, on my 2's, two runs of AQ Type 6 outperformed a pair of $3800 Tara speaker cables. The Tara's were just sitting in my closet unused and I still went out and bought new cables.