Will you be using these bookshelf speakers with a subwoofer? Or will you be using them just by themselves?
It's also important to note that the speakers are only half of the audio equation. The other half is your room. A room with lots of flat, hard surfaces is going to work best with different speakers than a room with lots of irregular and/or sound absorbing surfaces. And a really big room will work best with different speakers than a really small room.
So please tell us as much detail about your room as possible! Basic dimensions; is it closed or is it open to other rooms? Are the walls, floor and ceiling bare and flat? Or do you have acoustic treatments, carpet, thick drapes, lots of plush furniture, etc.?
And what is your basic set up? About how far away are you sitting from the speakers? Are the speakers really close to any walls, or are they on stands out into the room?
You want your speakers and your room to work together, rather than against one another. There are many different rooms, which is why there are many different speakers! At $500/pair, there are many choices, so we want to recommend to you the speakers that will work best in YOUR room
