After searching the head-fi for combination and opamp orders...
my current second best for the P4 is AD8599 (class A)+ HA-5002(Buffer) + ISL 55002 (G/V)
Edit: After few hours of listening, I changed LT1355 in place of ad8599, this bring the sound stage closer to listener. I think this is the best now.
Edited by civilaudio - 3/14/12 at 12:39am