I believe it really depends on your other components and what you're trying to achieve. However, I would presume that it would be easier or more logical to change your amp than the DAC itself hence tube amps, and tube rolling. Most high-tier DACs seem to exhibit the same type of sound, which is to be as transparent as possible as to not color the sound in any way. HOWEVER, there's a matter of speed and energy of the DAC which may be a large factor in the synergy of the system. This is because I personally hated my Gungnir for being way too shouty and explosive; I preferred the more relaxed X-Sabre much more with the HD800, and even the LCD3. However, others like purrin love this explosiveness in sound. This explosiveness/shoutiness isn't necessarily something that represents the FR, but is nonetheless a deciding factor. I believe the better the DAC, the better the peculiarities of the sound gets, such as smoothness, explosiveness, 3D stage, imaging precision, rhythm/prat, realism, dynamic volumes of instruments, blackground, "plankton," micro/macro detail, etc.