Amps totally have different sound qualities even when measuring well. The changes are just very subtle, but definitely perceptible. More noticeable than 320kbps mp3 vs 16/44.1k. If you can consistently pick out lossy vs lossless, you can definitely hear changes in amps. BTW, that's like 1% of the population. Maybe if you can't reliably hear the difference, you fall into the majority of listeners.

That being said I've never heard a headphone only sound good on certain amps. If I like the headphone, I will like it on any amp. If I don't like a headphone, I probably won't like it on any amp. It's not a big deal, but a way to achieve a sound closer to what you'd like (changes in dynamics and soundstage which can't just be EQ'd in)

If you didn't like the Dianna, a different amp won't make you like it. You might like it more, but I'm sure there is something else out there that will actually wow you regardless of what amp it's being run on.