I have the opposite effect when using my HE-Adapter with my Burson Timekeeper. Nothing seems limited, restrained, or restricted. The sound is more open, more dynamic and effortless on the Timekeeper. The sound from the Timekeeper is bigger than the sound from my Pro iCan. Neither of them gets hot and I have to turn down volume on the amp when I use it considerably. The HE-Adapter shouldn't have that kind of effect on the sound. Something may be wrong.