trivium911
500+ Head-Fier
I own the Q1 and the HE-400i and, based on my listening preferences, there is plenty of power to spare. That said, the HE-400i does sound fuller and demonstrates improved soundstage with a higher quality amp such as the Project Ember.
Hmm i would say there is just enough power, might be lacking for some classical music or just enough depeding on how loud you want it. Im running my 400i out of the little dot 1+ hybrid tube which is much better suited, ended up giving my Q1 to my brother to use with his blackberry as i have my fiio x3ii anyways for portable and dac which is technically better. Ever since i bought my x3ii ive been used my x1 strictly for the gym and have not had alot of use for the q1. I also picked up a cheap used xonar d2 soundcard which i plug into my little dot instead of the q1 usb dac which is what i used before.
There was nothing bad about the q1 with the 400i... the warmth was nice, just lacked some authority and as someone mentioned the 400i sound better with a thicker sound such as found on a Hybrid tube amp.