What difference will the 4.4mm or 2.5mm balanced output make to the sound?
Portable DACs usually give you a simple 3.5mm single-ended output wherein you can plug your IEMs into them. But nicer DACs also feature a Balanced output, usually through a 2.5mm or 4.4mm port. IEM manufacturers have started including Balanced cables with a 2.5mm or 4.4mm plug to take advantage of the balanced output. And several upgrade cables are now available for virtually all IEMs having detachable cables that also feature the 2.5mm or 4.4mm plugs.
A balanced output on your DAC, in general, minimises crosstalk between the left and the right channel and can make your music sound open with added depth and layering. It also offers more power and less distortion at higher volumes and can make the bass sound tighter and more deliberate.