I use Beyerdynamic T1, Beyerdynamic DT 880 Pro 600 ohms, and Sennheiser HD800. Most of the time the I can get enough loudness when listening to music (Albums). But during recording and mixing, sometime the headphone output is not loud enough for listening to the individual tracks.
Now I add Dr. DAC2 DX as a headphone amplifier for UR824, I can get more loudness, better clarity, punch, and detail. I connect it through the SPDIF output of UR824, to the SPDIF input of Dr. DAC2 DX.
But still, I would love to have louder and better headphone output direct from UR824 if that is possible