Between the D5 and D4 it doesn't really matter too much, as long as you use a sub on all your listening. Too me the two sound identical except for the D5 extending a good bit lower. This will mean that you could cross your sub over lower if you wanted to. I have heard others (at least one other anyways) say that they can tell a difference between their midranges and they preferred the D4. Oh, also, the D4 puts out a prodigious amount of air from the rear port. Auditioning them the saleman had set one of them up about a foot in front of another speaker. When I played a bass heavy track there was this horrible sound. The only conclusion I could come to was the air out of the rear port was causing the driver on the speaker behind it to flutter. I moved the speaker a foot further into the room and the sound went away. From your setup I don't think you'll have a problem, but just so you know. The D5 is $300 more than the D4.