Is this normal behavior? Can I force those sounds to be played through the DAC as well? Thanks for your urgent reply!
hold alt and click the little speaker guy in the top menu bar, it'll come up with a list of available output devices.
i tend to find that sometimes my mac will automatically mac an aggregate device which kind of combines all your audio devices into one, but this has always been a bit crap for me so just select the NuForce.
On a side note maybe look into a better player then iTunes... I switched to Clementine and found that i was hearing things i hadn't heard before in tracks that I know really well. (i haven't done a proper test of this so of course that is completely an objective phenomena but i prefer it)
One key thing you must do for best sound quality. Move all of the digital volume control sliders to 100%. Not 99.9% but all the way to 100. This is the only way to get any software system to output the bits from the file without any processing. Once you get them output with zero processing all software sounds the same. If the sound is to loud use an ANALOG volume control.
Doing anything else will reduce the dynamic range. Your software tries to make up for this by dithering but t can't really work as well as the above.
I don't disagree that have the volume at 100% will give bit accurate audio but
to be honest i doubt if there's anyone who could tell the difference between a file that has had it's volume lowered digitally and one that has been lowered in the analog realm in a blind test.
Turning the volume down in the analog domain still reduces it's dynamic range.
(Dynamic range being the difference between loudest and quietest parts of the track. USABLE dynamic range being the difference between the noise floor and loudest sound a system can make, i.e. lest say your room has a noise floor of 40dbspl (pretty average) and your music is peaking at 85db, it's dynamic range is 45db, if you turn it down to say 75db, the noise floor won't change with it, so you now have dynamic range of 35db. this is totally different from dynamic range compression which doesnt happen when you digitally lower the volume. That's the way i understand it anyways, please correct me if i'm wrong)