I mean, I can hear a difference, and I had both DACs connected to my headphone amp at the same time, so i only needed to flip a switch on my amp to go between the two audio sources. I could clearly hear that the new DAC was more detailed, more precise. But the old one was more natural. And I don't mean natural as in I am used to it, or it sounds "normal." I mean it sounds more natural in that the audio sounds more like they're happening in real life, and not obvious sound effects, ya know? Like you can hear a door open in one game and be like "wow, that's an obvious sound effect" but with the Surround sound setup it gives it a sort of reverb you'd actually expect to hear in a real room which takes a door closing from sounding like a sound effect, to sounding like someone just shut the door to your room.
It's because in real life when you hear a sound, even if the sound is 90 degrees to your right or left, you still hear it in both ears, you hear that echo coming off the wall on the opposite side of the source of the noise, being picked up by the opposite ear. With headphones, you don't get that, you hear the audio source directly to your right, only in your right ear since headphones aren't loud enough, and generally your opposite ear is sealed off anyway that you do not get those reflected sound waves. It's that feature that makes sound effects and voices sound more realistic.
