I'm one of those guys that tend to use Auricaps as coupling caps in my projects. However, I'm ashamed to say that the decision is not based on experimentation, but rather a "better-safe-than-sorry" attitude. Kind of like "Pascal's Wager". My use of Auricaps is based on its reputation from other builders, and truth be told, I have no idea how they stack up against cheaper components.As far as "boutique" parts are concerned, Auricaps are actually on the "cheap" end of the scale. Check out the crazy prices of Hovland and Jensen at www.partsconnexion.com
I'm not sure if I can use the term "sound good" to describe any capacitors when used as coupling caps. My feelings on coupling caps is the same as those for interconnects. Their use cannot make a system sound better, only worst. It's just that the better ones degrade the signal less, or in a less objectionable way than the poor quality ones.
Gar.