Bought one through Audiocubes one year ago, very good build quality and superior sound. P-1 could work very well with most of the cans, I've tried R-10, L-3000, W-2002, Proline-2500, all sounds warm and bright.
I had a trip to Tokyo on X'mas time, visited one of the Qualia building and it is P-1 they used to drive Qualia 010.