I received some RE-600s a week ago and put about 100 hours of musical burn-in time with them, having lived with RE-262 the last couple years.
What I am hearing is a slight hardness in the upper mids and more neutral presentation (as opposed to warm or cool), and negatively impacts my enjoyment of the music. Perhaps I am too used to the liquidity and mid-range warmth of the RE-262?
Yes, they are very spacious and great soundstage, better even than the RE-262 perhaps because the highs are not quite as rolled off as the RE-262. They handle complex music well and have good texture and depth in the bass.
...But those slightly hard upper mids. And without the warmth, I have trouble relating to the reviews that call the mids "lush". Do I need to put some more burn-in hours on them or is this their final character?