[Jbucla2005]

I'm using a pre-amp and controlling the volume from my desktop while setting my tube amp at about 35% volume. I found this worked better than going straight to the amp from the dac. Is there any logic to this or am I just imagining the benefits? I feel that by lowering the volume of the source I'm adding more of the tube sound from the amp.

 

[Roseval]

Depends.
If the distortion generated by the tubes is constant, it doesn't matter.
If the distortion generated by the tubes increases with volume, set the volume to the max to get the full tube sound.