I was somewhat disappointed in the lack of power the QP1R has when paired with the HIFIMAN HE 1000. It seems that with many recordings even at a volume maxed out there just isn't enough dynamic range. I really thought this would be the best portable rig when reading the reviews. My Cypher labs Theorem 720 powers it much better. However, I am not sure the details are there as the DAC in the QP1R may be more refined. So is there a portable amplifier to pair with the QP1R that will be more powerful to drive the HEK? I would like some options to have a stack as I did with my iPod and Cypher labs Theorem 720, which is still one of the best sounding combos I have heard so far with any headphone other than planars.