@devilboy -- I had the Quicksilver headphone amp for a few months. I only sold it because I spent two much on the 2 channel setups in my house and needed some cash quickly.
I had the opportunity to listen to the Pass Labs HPA-1 a few months ago. I actually took my Aryas to the seller's house for auditioning. Let me just say this -- there is no comparison! As good as the Quicksilver is, the HPA-1 just digs out the details better but yet never loses its composure or sound harsh at any point. They simply made my Aryas sound even bigger and wider than with the Quicksilver.