Main reason why people do not like Grado is because (i believe) they are very source dependent (how to control the brightness). For portable amp, i think Phatlab Sassy so far is the best one for my Grado. Also, as many people who might already know, Grado is not as genres friendly as many other phones as well, especially if bass was the one they looking for. But for instruments Violin/Cello/Classical, Grado, in my personal opinion, still perform best in term of accuracy and realistic level, and they are very easy to drive.
I cannot elaborate on their source dependants, as I have not tried enough sources to have a good picture of that.
In terms of genre diversity, I would politely disagree. To my taste they can play almost any genre well (in this category, the ATH-AD-series for example is worse). But if there are to show their full potential and do what they were designed to do, it is indeed a fairly narrow type of music, namely little layered, acoustic music.
Try this: https://www.youtube.com/watch?v=hz1V0gaCsK4
What I meant is that Grados are generally overlooked in favour of RS1e. But out of all the Grados, i think the 325-series brings the most 'new' to the table in terms of the Grado sound. Which why I didn't go for the Alessandro, as they somewhat smoothen the highs.
This is crazy talk I just posted a pic of my 325is like last week! And THEY'RE JUST BRIGHT ENOUGH
so there lol
People always find them too bright and piercing. I never found them splashy. Aggressive, in-your-face, timbre-focused, treble focused, FUN...yes...but never hot.
We need more treble heads.