
@Charles > The master output runs through a higher quality DAC than the headphone or booth outputs do so there is a slight difference in the audible quality of the sound, but typically not so much that you'd notice or complain.
IEMs are great for being able to be used at lower levels than their over-ear counterparts, however you're not going to "widen the soundscape" simply by switching your in/on-ear monitoring; that would be done via signal processing.
I have an ear for audio quality, but I'm no audiophile and personally, I would love to have a great pair of IEMs but don't feel that adding a $400+ headphone amplifier would improve my experience of monitoring with a DJ mixer.