I have a set of Beyer DT990 250ohm cans and recently bought a set of MDR-1RNC also. With both headphones, I am listening to them through a MisterX M^3 amp with sigma6 power supply. The sound is very detailed, and not too digital at all. I like it, especially with my DT990. The source is a Marantz CD player. But, the hifi bug bites again. Where do I go from here to get even better sound? Should I upgrade my cans, amp, or something else?