Well, when I say you really need to listen to it, I say so neutrally.
While it was robust, I found the amp QUITE cool sounding. More blue than red. Kind of how I felt about older Krell equipment.
It was also a lot finer and more delicate across the mid to treble compared to say, early MOSFET's of the 1980's. When I heard the InnerSound ESL amplifier, it was moving in the direction of what I am calling the "modern amplifier sound" but, I don't know how to actually say it, I found the presentation rather stark.
So, LISTEN for yourself. :) It has many fans.
Best,
E