You are not really double amping the headphones (only the power of the second amp engaes the drivers), the first amp in effects boost the voltage of the signal to the second amp, as an active line stage or pre-amp would do. If you prefer this sound, then you may want to look at getting a dedicated preamp. I know I do, and much prefer my V200/HE500 combo when the signal is first passed through a Rogue 99 Magnum pre.
KP