There was a sharpness to the amp and the micro details were missing from some tracks.
It really depended on the dominant frequencies in the tracks but still.
Now if he thinks the Modi2U sounds like crap, I think that is definitely correct.
When I tested my friends Modi2U (mind you this is before I even found this site) there were so many missing details in my complex tracks.
If I just played like rap with male voices it was fine, but when it came to female voices or classical tracks with violin and other string instruments.... well it was clear that the instruments sounded flat.
And this was using my same Amp (O2) and my mrspeakers Aeon.
I also tried my Topping A30 with the Aeon, which is something I regularly listened to....
So I think it really depends on if you listen to music you know or don't know. You need to have a reference point when testing audio equipment. This is why for me I have a test playlist of songs I am very familiar with, but which also have either defects or difficult to reproduce microdetails that I can listen for to tell me about how much distortion there is.