I have the 683's and they're probably one of my favorite speakers to listen to. I recently upgraded to the CM10's and although they are probably more accurate, I still enjoy the sound from the 683's as much (if not maybe more) than the CM10's.
The bass can be a little over exaggerated in some rooms, but placement usually corrects this. I originally powered them with my Integra all in one and they sounded good. I then upgraded to the XPA-2 and that is when they really shined, not necessarily at low listening levels, but there was definitely a huge improvement at loud levels. As for over powering them, i wouldn't worry about it. I fed some serious power into the 683's when listening to a full orchestra (border line red lights on the Emo) and they take it with ease. Below is a video I made of the 683's with the XPA-2, the level in this video was border line painful and you can see the Emo is barely working.