What it means is that it needs 300-500 to sound it's best, so with only 30 hours on it, it's not even close to what it will sound like. I spoke with someone who's listened to a fully broken in one and it's going to be just like my AX-5 Twenty.
As for how it sounded, it was excellent, but didn't blow me away as it wasn't fully extended early in the day, but around 6pm when folks left I went into the room and sat in the middle seat. Without all the folks in the room and warmed up I was blown away. I am not trying to use to many exciting words since it needs to break in, but out of the box it was sounding better than many of the 7k DAC's I've heard in the last year. I'm coming from an Empirical Audio full done ODSE/SE which I actually think is on par with the Berkley Ref DAC mk 2. Some feel that the Berkley is better, but I've heard the Berk recently in my own system and feel my old ODSE/SE was better in a few ways and on par in the rest. This DAC will not sound its' best until it breaks in, but not sure where you got the 'just okay' from. What I heard when I sat in the sweet spot and with it at least warm was outstanding, but the ceiling will be much much higher based on what I was told it sounds like burned in. I also love how versatile it is and I fell in love with Roon too. That's now a much for me.