Difference between the 3 gains modes in Xonars cards

The different gain levels are all handled digitally on these cards. There is no actuall physical change of gain on the Asus Essense ST or STX &suspect not on the Xense card. They only set the max volume 1-3bits down from the max volume available at max gain. 64 & below ohm setting is 3 bits down, 64 -300ohm setting is one bit down from max volume & 300 ohm & above uses all bits. Front panel speaker output also uses the headphone amp & that is 2 bits down from max volume but matches the line out volume. The line out amps have lower physical gain & therefor uses all available bits thus giving better noise specs than the headphone amp does at the lower "gain" levels. Even at its worst the noise level is sufficient for all but the most highly sensitive IEMs. Even with 115db/1mW IEMs appear dead silent to me. IEMs the exceed this sensitity may not be quite so dead silent though.

On te other hant the Claro halo XT headphone card which uses the same headphone amp appears to have jumpers to physically change the gain of the amp.  

Quote:

Originally Posted by Delerue 

Thanks, germanium, for your very detailed reply. So, in practice (even considering the loudest noise level in the worst case), there's nothing to lose in using other gain settings besides 'Extra High Gain', except for the final volume, right?

Correct People who think there is a difference think so because they are not truely matching the true volume levels. .02of a db difference will make the louder one seem better providing clipping doesn't occure. This is due to the fletcher munson ear sensitivity curves. Even very slightly louder sound will sound fuller & more pleasing. I have taken the time to evaluate the different gain levels at matched volumes & to me there is no difference in sound. Note that even if there were a real difference in gain with this particular headphone amp there would still be no difference in sound as the performance of this amp remains the same up to at least 10MHz!!!! It's the beauty of current feedback amps that they are unaffected by final gain. The only disadvantage is slightly poorer D.C. properties as manifested by the slightly higher D.C. offset at the output

Note that the noise level does not change when you change the "gain" level.