I visited my local headphone store to demo the Mentors again, and boy, was I impressed.
Along with the Mentors, I auditioned the universal UM Miracle and the SE846. I tested them straight out of an iPod Classic (7G), an Android phone with Poweramp, and the iPod Classic amped with an iBasso D6.
Without amping, the Mentors had a full, powerful sound that really wowed me. Overall, the bass was strong but controlled, the mid-bass punchy and exciting. The SE846 had just as much bass, but it sounded a bit more congested than the Mentors.
The presentation of the midrange was superb. With some of my choice rock songs, vocals were clear, and instrument separation was top notch. I felt that the Mentors were a little v-shaped, but the mids didn't take a back seat to rest of the sound.
Treble was well extended, and here is where the Mentors really excelled. I am not a big fan of strong treble, but with this IEM, the highs were delivered with a lot of clarity, without sounding grating to my ears.
Amped with my D6, the treble were boosted quite a bit, which resulted in some harsh highs on some of my rock and dance tracks. There was a slight gain in bass quantity, but this also resulted in a slightly more boomy sound on bass/beats heavy dance tunes. The midrange however retained much of its melodic tone.
Overall, the Mentors delivered a very coherent sound, which was full and exciting. With strong but well defined bass, clear and controlled highs, and a beautiful midrange, this was really a treat to my ears, with or without an amp.
In comparison, the Miracles sounded too flat. It had oodles of clarity but none of the fun.
Ultimately, I ended up buying the Mentors. This is my first CIEM, and I am eagerly awaiting the day I get my hands (and ears) on them.