Everyone's going to have their own opinion on that, and no one hears exactly what you do. From my experience, though, night & day difference? No. Noticeable? Yes. An improvement? Sometimes for sure, not always. I thought my M50's sounded lousy whether plugged into dac/amp or straight into my MacBook Pro years back. But I thought my HE-400 sounded great out of both, and often used them unamped. So I got rid of the dac and amps I had. My 600-ohm Beyers sounded thin without amping, so that's why I got an Objective amp, and then later moving to the Magni/Modi. It wasn't night & day, but it was a noticeable improvement, and enough for me to personally justify spending $200 on the M&M. But if I ever end up getting my HE-400s again, I wouldn't hesitate to use them unamped.