I have maybe 30 hours on the amp and honestly sense very little difference in SQ since the time I connected it to my system and have run it in. I am really impressed with the crystal clarity of the music, along with very large soundstage and tonally very balanced top to bottom. I got the Sparkos op amp, recommended for a softer musical presentation by Warren. At the moment, I am enthralled with the sound of the amp in my system, but will swap back my McCormack amp as means of comparison after 100 hours. However, at this point, I am of the opinion that this amp is a huge advancement in the art of Class D amplification, very different than my past experiences with Red Dragon, Nuprime and Bel Canto, although I am sure that all these Class D companies have greatly stepped up their game since my audition of their amps several years ago. More later, but I am really happy with what I am hearing so far.