they sound good out of the x3, but better with a good headphone amp in the loop.
but they really shine with XD50, much better really, and with a good amp in that loop
they are reference class! (e.g. a ray samuels amp). hallucinatory. as DS nuts pointed
out more flat response phones sound better with with the x3 and warmer ones with the DX50
its really true, and worth the investment in the DX50 if you have the X3 and want to brining out
the best in phones like the cks1000s and gratitudes....its not a subtle difference, its a magical