@tomcarr This feature is beneficial if you have an inverting phase preamplifier or amplifier. By default, most units deliver signal in proper phase, but some units deliver on inverted phase. Think of this as a perfect sine wave tone that gets flipped or inverted. It should sound the same, but its timing is slightly different and may hit the ear in a way that is more or less impactful. If for instance you have a proper-phased amplifier and inverted-phased preamp, and neither have the ability to toggle the phase, the D-03X will give you the ability to correct this.
You can experiment with this yourself. If your system is properly phased, inverting the phase on the D-03X should result in a slightly softer delivery, and soundstage may even be pushed back a little. You should opt for which ever setting sounds slightly crisper.
FYI I used to work with a Tom Carr In Philadelphia many years ago. If you are the same Tom Carr, then hello!
Juan Charvet
blisshifi.com