Before I really was into audio, I use to just plug in headphones into the jacks of my desktop. Its weird because there was 2 headphone jacks (one on the front and one on the back). If I can remember I think the front jack sounded better and probably like same computers DAC's I've heard. But the back port how ever sounded really fat, a lot of mid bass, muffled and lacked clarity. I did notice a difference to when I got the FiiO E07K my first Amp/DAC. Things became a little more separated, treble became sparkly and clear and the mids sound neutral instead of that disgusting muddiness. But when I upgraded from the FiiO to the Schiit Asgard 2 and Modi I heard no difference.
To be fair, I think the modi is super overrated. I couldn't hear any difference between it and my sound blaster so I returned it. When I got the Audio-GD, I could clearly hear an improvement
I'm not sure why people seem to love it so much. A sound blaster omni costs less and sounds as good and can do more.