Seems like the entry level headphone for Crack listening is something like a used HD600 for maybe $250 used. Would there be any interest in a kit that starts with a very bang for the buck good sounding headphone and modifies it with improved cabling, damping and electrical tweaking to optimize it for the Crack? Price might be in the $100-$150 range, including the headphones. Not saying it will stomp HD600s, but so far I'm pretty happy with our experiments and one nice advantage is the design has a closed back.